The Prime Minister will hold a special Cabinet meeting on Thursday ahead of her keynote speech on Britain’s exit from the European Union in the North East the day after.
Mrs May held a Brexit “war cabinet” meeting at Chequers earlier in the week to thrash out the details of the next steps of negotiations with Brussels.
She said: “On Thursday, I told the Cabinet committee at Chequers that the deal we negotiate with the EU must present an ambitious future for our great country.
“Next week I will present the committee’s conclusions to an additional session of the full Cabinet before travelling to the North East on Friday to give a speech setting out this Government’s vision of what our future economic partnership with the European Union should look like.
“Delivering the best Brexit is about our national future, part of the way we improve the lives of people all over the country.
“So I concluded the meeting by reminding the committee that the decisions we make now will shape this country for a generation.
“If we get them right, Brexit will be the beginning of a bright new chapter in our national story, and our best days really do lie ahead of us.”
The Government will pursue a policy putting Britain outside a customs union with the EU but matching Brussels rules in certain sectors in an attempt to achieve “frictionless” trade.
But European Council president Donald Tusk said the Brexit plans are an “illusion”.
He will meet Mrs May in No 10 for talks on Thursday lunchtime.
At a press conference on Friday, Mr Tusk said: “It looks like the cake philosophy is still alive. From the very start it has been a key principle of the EU 27 that there can be no cherry-picking and no single market a la carte.
“This is, and will continue to be, a key principle, I have no doubt.”
The Prime Minister’s deputy has warned the devolved administrations they risk damaging the Westminster Government’s “ability to act in the national interest” if they push for “different sets of rules” across the UK.
David Lidington said different standards is areas such as food safety and chemicals standards could hamper the government when it is trying to strike trade deals on behalf of the entire country.
He told The Sunday Telegraph: “We could choose to leave as a country split and an economy disjointed, struggling to make our way in a new world outside the EU.
“Or we can come together as one United Kingdom, confidently seizing new global opportunities as we build a prosperous, secure nation fit for the future challenges we will face.
“By maintaining legal UK frameworks where strictly necessary, we retain our ability to act in the national interest when we need to - protecting our nation’s security or signing trade deals with the growth markets of tomorrow, using the leverage and the diplomatic network of the UK to sell Islay whisky, Caerphilly cheese and buses from Ballymena throughout the world.”
Labour leader Jeremy Corbyn will make a speech on Monday setting out his party’s approach to Brexit.
But a letter backed by more than 80 figures across the party exposed the internal divisions on how to proceed.
The group warned the leader his plans for investment in schools, hospitals and social care would be unfundable unless the UK stays in the EU single market.
In a statement, released to the Observer and backed by senior figures including Chuka Umunna and Lord Kinnock, said: “Labour must clearly and unambiguously set as a negotiating objective the goal of remaining part of the European economic area, in order to participate on a permanent basis in the single market.”