The former Army helicopter pilot and two fellow crew members will launch to the International Space Station (ISS) on a landmark flight from Baikonur Cosmodrome, in Kazakhstan.
To mark the launch, #BritinSpace, #Principia - the name of the six-month mission - and #TimPeake are all trending on Twitter.
Here, we feature some of the best of those comments.
@Astro_Matt27 tweets his best wishes to the Chichester-born astronaut:
@mccartanfi tweets her excitement ahead of the launch, scheduled for 10:30 GMT:
@angegarrod and @joannajury are also looking forward to the launch and using #BritinSpace - the highest trending hashtag ahead of the historic spaceflight:
Notable names from the world of sport and TV are also anticipating lift-off, with cricket commentator @Aggerscricket and adventurer @Benfogle adding their best wishes to their fellow countryman:
And just in case he hasn't had time to check the forecast in Kazakhstan for Tuesday, @bbcweather posted this helpful update for the intrepid 43-year-old:
Compiled by Stephen Fottrell.

The new wombat was born at the Richard Underwood Nature Refuge in St George, in Australia.
The baby, known as a 'joey', brings the total number of the animals to 251 and was the first of its species to be born at the wildlife refuge for five years.
The main threats to the wombats are wild dogs, disease and competition for food from kangaroos.

Mr Natzler has served as acting Clerk since the retirement of Sir Robert Rogers last year.
A panel led by Mr Bercow initially recommended that Australian Carole Mills take the role but MPs objected and she has since withdrawn.
News of Mr Natzler's appointment was met with cheers by MPs in the Commons.
The recruitment of a new Clerk, Parliament's most senior legal and constitutional adviser, has been dogged by argument over the past nine months.
MPs said Ms Mills, the original choice of the House of Commons commission who works in the Australian Parliament, did not have the relevant constitutional experience and accused Mr Bercow of a "stitch-up".
Mr Bercow insisted that the appointment must have the confidence of MPs and "paused" the recruitment process before re-starting it.
As part of a modernisation of procedures, the current responsibilities of the Clerk will now be split, with a new post of Commons director-general taking over responsibility for the day-to-day commercial and administrative functions of the Commons.
Announcing Mr Natzler's appointment in the Commons, Mr Bercow said he had been chosen from a field of four candidates.
Welcoming the appointment, David Cameron joked that Mr Bercow had "gone to the ends of the earth" to find the most qualified candidate and he was "very glad he found the right answer right here in Britain".
Labour leader Ed Miliband said Mr Natzler's appointment was "well deserved".
Before Sir Robert's retirement, Mr Natzler served as Clerk Assistant for many years.
Maj Tim Peake will become the first British European Space Agency (Esa) astronaut to go into space, on Tuesday.
[NEXT_CONCEPT]
One of the world's rarest species - the northern hairy-nosed wombat - has been given a much-needed boost with a brand new arrival.
[NEXT_CONCEPT]
David Natzler has been named as the next Clerk of the Commons, ending a controversial process which pitted Speaker John Bercow against some MPs.