A delegation including independent MEP Steven Woolfe, former trade minister and ex-CBI chief Lord Jones of Birmingham, Leave Means Leave co-chairman John Longworth and Labour Leave chairman John Mills travelled to Brussels for the talks.
Mr Woolfe said Mr Barnier had spoken to many UK Government representatives and backers of Remain but this was an opportunity for him to meet a cross-party group of convinced Brexiteers who could get across the message that EU withdrawal has significant support in Britain and will not be overturned.
The former UKIP MEP said: “We told him that a trade deal should include goods and services.
“Our message was that if we don’t have an inclusive agreement for goods and services, the British public will say we should walk away with no deal.”
Mr Longworth said he made it clear to Mr Barnier “no trade deal is better than a bad trade deal” and there was “no way the UK is going to reverse its decision on Brexit”.
He said Brexit supporters would “not be prepared to negotiate away our newly-won economic freedoms” to secure a deal with the EU.
And he warned Mrs May’s hopes of a bespoke deal with the EU would be dashed by Brussels.
He said: “It is very clear that the idea of a special relationship deal that the Prime Minister keeps talking about is out of the question.
“I have no doubt that Britain will thrive with or without a trade arrangement with the EU so long as the Government leverage our newly won economic freedoms.
“I am concerned that the EU’s negotiating team is looking increasingly out of step with the mood of many of the EU27 national governments who recognise the importance for their own economies that a free trade deal is reached with the UK.”
The meeting came after former UKIP leader Nigel Farage held talks with Mr Barnier on Monday.
Francis Grove-White, deputy director of the Open Britain campaign for close ties with the EU, said: “We have reached peak Brexit.
“We must protect jobs and our economy, and that means staying in the single market and the customs union on a permanent basis.”