The imperative phrase go to Bath (and get your head shaved) is said to a person that the speaker does not wish to see again.

This phrase refers to Bath, a spa in south-western England, where one goes to take the waters.

With one exception, the phrase first occurs in taunts directed at two politicians, Henry William Hobhouse and John Arthur Roebuck, who were both associated with the city of Bath (cf. explanatory notes ¹ & ²)—these are the three texts in which go to Bath occurs in taunts, in chronological order:

1-: From the account of the public meeting that designated the several candidates for the parliamentary constituency of Finsbury—account published in The Times (London, England) of Thursday 8^th January 1835:

Mr. Hobhouse ¹ said he never had a conversation on politics with the learned serjeant in India, and added, that if he had been reputed a Tory there, the serjeant had been regarded as a Radical Reformer. (Cries of “Oh, oh!” “We are tired of you, Hobhouse;” “Go to Bath;” “It’s very cold!” and shouts of laughter. Some person in the crowd also pelted an egg at Mr. Hobhouse, which struck a gentleman on the hustings.)

¹ The British politician Henry William Hobhouse (1791-1868) failed to be elected as a Member of Parliament for the constituency of Bath in 1832; in December 1834, he retired from the contest for Bath while accepting to be put in nomination for the constituency of Finsbury—where, however, he failed to receive sufficient support.

2-: From John Bull (London, England) of Sunday 18^th September 1836:

CANADA.
Extract from a letter, dated Peterborough, July 17, 1836.

The general election of Members for the House of Assembly has closed a week since, and we have, throughout the colony, given the Radicals such a drubbing as they will not forget for some years. I do not suppose such a re-action in public opinion, and so very decidedly expressed, can be found in the annals of electioneering in any quarter of the world, except where revolution has held the sway. You may tell Joey Hume that the “totlle of the whole” of his treasonable arguments about “baneful domination,” is scouted throughout this colony, and he is heartily dispised. And you may tell Roebuck ², “to go to Bath, and peddle his legal wares, as a hired and paid politician, for more beneficial purposes than meddling with us.

² The British politician John Arthur Roebuck (1802-1879) was elected as a Member of Parliament for the constituency of Bath in 1832; he failed to be re-elected in 1837, but he regained the seat in 1841.

3-: From the account of an anti-corn-law public meeting held at Finsbury, published in The Morning Chronicle (London, England) of Thursday 31^st January 1839:

Mr. Roebuck came forward, and was for several minutes unable to obtain a hearing. He said he had a few words to say upon the subject of the abolition of the corn-laws, because he thought it was important to adopt every possible means of getting rid of them [cries of “sit down,” “go to Bath,” and great uproar].

The following from The Evening Chronicle (London, England) of Friday 1^st February 1839 evokes the taunt directed the previous day at John Arthur Roebuck:

A fraction of the working class seems determined, if possible, to impede the movement for the repeal of the Corn-laws, and to throw into confusion every meeting which is held for the purpose of petitioning the Legislature on that subject. […]
[…]
There is a glaring inconsistency in this refusal to petition, or allow others to petition against laws which they themselves denounce as most ruinous. They will not petition, they say, because the Legislature is so notoriously hostile to the repeal, that there is no hope of its being carried. And yet for the universality of the suffrage they have petitioned, are petitioning, and will continue to petition. Is the Legislature, then, so friendly towards universal suffrage that they anticipate its being carried? Whether the answer be yes, or no, the interruptions of the anti-Corn-law meetings are alike condemned. If there be hope for the suffrage, much more is there hope for Corn-law repeal. If there be none, and the object is simply to discredit the Legislature by its refusal, that object would be far more effectively realised by the refusal to the working man of the bread that he earns, rather than by the refusal of the vote that he claims. This view of the subject was pointedly urged by Mr. Roebuck at the Finsbury meeting. And what was the answer? “Go to Bath.” Whatever other claims these parties may possess or lack to the right of mingling in the political arena, they have at least demonstrated their possession of the worst qualification exhibited there, and evinced their proficiency in the dishonest tactics of faction.

The only early use of go to Bath that does not occur in a taunt directed at a politician associated with Bath is from Family Stories.—No. III: Grey Dolphin, by Thomas Ingoldsby ³, published in Bentley’s Miscellany (London: Richard Bentley) of April 1837:

“Hear you, Ralph de Shurland, Knight, Baron of Shurland and Minster, and Lord of Sheppey, and know all men, by these presents, that I do hereby attach you, the said Ralph, of murder and sacrilege, now, or of late, done and committed by you, the said Ralph, contrary to the peace of our Sovereign Lord the King, his crown and dignity: and I do hereby require and charge you, the said Ralph, to forthwith surrender and give up your own proper person, together with the castle of Shurland aforesaid, in order that the same may be duly dealt with according to law. And here standeth John de Northwood, Esquire, good man and true, sheriff of this his majesty’s most loyal county of Kent, to enforce the same, if need be, with his posse comitatus.”
“His what?” said the Baron.
“His posse comitatus, and—”
“Go to Bath!” said the Baron.
A defiance so contemptuous roused the ire of the adverse commanders. A volley of missiles rattled about the Baron’s ears. Nightcaps avail little against contusions.

³ Thomas Ingoldsby was the pen name of the Church of England clergyman, novelist and poet Richard Harris Barham (1788-1845).

The phrase apparently occurs in the following, from the account of a law suit brought before the Court of Calcutta, published in the Bombay Gazette (Mumbai, Maharashtra, India) of Friday 18^th October 1839:

The first officer of a ship touched his hat to the Skipper.
‘May I go on shore, Sir?’
The Skipper in the exuberance of an accomodating [sic] spirit replied ‘you may go to the devil if you like.’ […]
[…] The officer having full permission to go to the devil, was of opinion, that it implied such a long leave as amounted to a virtual discharge from the ship, and he consequently landed, refused to return, and sued his commander for wages due. […]
[…]
[…] One of the learned Magistrates remarked to the Captain that it was a pity he had not told his mate he might go to Bath which in Calcutta would have been almost as figurative, and the ingenious argument put forward on the other side could not have been raised.

The phrase occurs in this poem, published in The Bell’s New Weekly Messenger (London, England) of Sunday 9^th January 1842:

SONG OF THE SENTIMENTAL.

They bid me, Jessy! seek a wealthier lot,
Far, far from thee across the unruly wave:
Yet though thus parted, thou’lt not be forgot,
Until at strangers’ hand I find a grave
                    In some lone path.

And whilst in distant lands this heart shall beat,
Wilt thou upon me one fond thought bestow,
Or heed the hours that creep on till we meet?
Say that thou wilt—dearest—before I go—
                    “Oh! go to—Bath!”

The earliest occurrence that I have found of the extended form of the phrase, go to Bath and get your head shaved, is from The Era (London, England) of Sunday 22^nd April 1849:

“Go to Bath” is a very common expression. The addition of “and get your head shaved,” rendering the phrase slightly humourous [sic]. Why people are recommended to go to Bath at all, unless a disorganization of the liver renders a course of the nasty hot water requisite, we are at a loss to conceive. Still more are we puzzled to understand why that peculiar locality is esteemed so favourable to the operation of depriving the “caput” of superfluous hair, unless a predisposition to monamania [sic] among the inhabitants renders the practice of the “tonseurs,” from its extent, more perfect than elsewhere.

The second-earliest occurrence of the extended form of the phrase that I have found is from the account of a court case, published in The Norfolk Chronicle and Norwich Gazette (Norwich, Norfolk, England) of Saturday 7^th April 1860:

The evidence for the defence in this case was proceeded with.
Joseph Bowyer, gardener to the Rev. Mr. Cubitt, the person who accompanied Mr. Fabb on the 1st September, corroborated Mr. Fabb’s evidence. In cross-examination, he said he was sure that the words used by the defendant to plaintiff were, “Go to Bath.”
Mr. O’Malley professed his ignorance of the signification of this popular expression.
The Lord Chief Justice.—It is common enough, and I have usually heard it with an addition, “Go to Bath, and get your head shaved.” [Laughter.]
Mr. O’Malley.—l have heard “Go to Jericho,” but not “Go to Bath.” [Laughter.] The expression which I am instructed the defendant used was something more characteristic of the Englishman all over the world.
The Lord Chief Justice was surprised that Mr. O’Malley should never have heard so familiar a phrase, and informed the learned counsel that it was equivalent to “Go about your business,” &c. [Laughter.]