She will then be out of the room when the other 27 leaders discuss her Brexit proposals over lunch, and will find out about their reactions only when summit chair Donald Tusk briefs her separately afterwards.
As the European Union sent London to rework its Brexit plan, British PM Theresa May insisted it will not accept a second referendum - hours after the Tory treasury minister admitted that another vote could happen "within months".
"I want to be absolutely clear - this Government will never accept a second referendum", she said.
'We gave people the opportunity to make a choice.
While the warnings are not dissimilar to others that have been made, they underline the potential for disruption that could occur after the official leaving date next March.
The British Pound has erased all of its gains on the day after a series of disconcerting comments made by various European politicians connected to the Brexit summit taking place this week.
Most EU leaders "would welcome a situation where there is the possibility of the British people putting things into perspective, seeing what has been negotiated, seeing the options, and then deciding once and for all", he added.
She emphasised that the British public would not be given another vote on the matter, in spite of increasing calls for this.
A senior United Kingdom official said her message to them was "we all recognise that time is short but delaying or extending these negotiations is not an option".
Why do people keep talking about "Chequers" - what is it?"We can also clarify that most checks can take place away from the border, at the company premises or in the market".
"All these things will come back and we'll see more and more pressure, and (May) will have a deal she won't be able to bring back to the House of Commons because it'll be lumbered with loads of other European Union demands, so she's going to have to have something else", Davis told the BBC.
There are fears it could take an hour to process a lorry after Brexit
Mrs May is believed to have said the proposal would create a customs border in the Irish Sea.
"Others out there have been sceptical about the ERG, they don't want to be labelled swivel-eyed but we stood on a manifesto pledge to deliver Brexit, not remain half in half out". "So I don't think this really takes us anywhere, we're still stuck in a pattern of deadlock on this", Euronews' London correspondent Vincent McAviney told Good Morning Europe on Wednesday.
In an outspoken attack, he accused her of playing "Russian roulette" with the country and treating her own MPs "like children who belong on the naughty step" over Brexit.
She told them: "I know we won't agree on every detail but I hope you will respond in kind".
Barnier, mandated by European Union leaders to conduct negotiations, has called Chequers a starting point but not an end deal.
MP for Hemel Hempstead since 2005, he was sacked from the government by the prime minister previous year and then knighted in a move widely seen by MPs as Mrs May attempting to buy his future loyalty despite his pro-Brexit views.
"What we need in the withdrawal agreement is a legally operational backstop which fulls respects the territorial integrity of the UK".
But now, Mr Barnier, revealed, there was a Plan B; an "improved" proposal.
He added however that when Britain leaves the EU, Ireland will lose a valuable ally on taxation and globalisation issues.