In her keynote speech at the Tory conference, the Prime Minister will declare that next year’s departure from the EU is a “moment of opportunity” for the UK that will lead to a brighter tomorrow.
“I passionately believe that our best days lie ahead of us and that our future is full of promise,” she is expected to say.
She will take a swipe at the EU by insisting Britain will thrive whatever the outcome of the Brussels negotiations.
“Don’t let anyone tell you we don’t have what it takes: we have everything we need to succeed,” the Prime Minister will tell the Tory faithful.
And in a scathing attack on Labour, she will accuse Jeremy Corbyn of alienating millions of “decent, moderate and patriotic” Britons.
Mrs May’s passionate call to arms will close a Tory conference in Birmingham dominated by Cabinet calls for the party to end the Brexit infighting and unite around the Government’s proposal for an EU trade deal.
Her hour-long speech, entitled: “Our Future Is In Our Hands”, will highlight how countries across the world stand ready to trade with a newly independent UK.
Mrs May will promise that, in the coming months as the Brexit negotiations reach a climax, the Tories will always act in the “national interest” and put the needs of hard-working people first.
Signalling her desire to dominate the centre ground, the Prime Minister will accuse Labour under hard-Left Mr Corbyn of abandoning “decency” in political discourse.
“Millions of people who have never supported our party in the past are appalled by what Jeremy Corbyn has done to Labour,” she will say.
“They want to support a party that is decent, moderate and patriotic, one that puts the national interest first, delivers on the issues they care about and is comfortable with modern Britain in all its diversity.
“We must show everyone in this country that we are that party a party that conserves the best of our inheritance but is not afraid of change, a party of patriotism but not nationalism a party that believes in business but is not afraid to hold businesses to account.”
She will say that the Conservative Party recognises “the good that government can do but knows that government will never have all the answers” and “believes your success in life should not be defined by who you love, your faith, the colour of your skin, who your parents were, or where you were raised – but by your talent and hard work.”
Brexit news: Theresa May will issue a patriotic speech tomorrow
Mrs May will also signal her determination to stand up for the UK, saying the Tories are “a party of Unionism, not just of four proud nations, but of all our people”.
And mocking Labour “for the many not the few” slogan, the Prime Minister will say that the Tories stand “not for the few, not even for the many, but for everyone who is willing to work hard and do their best”.
Mrs May last night dismissed her warning from her business minister Claire Perry that a no-deal Brexit would be “catastrophic”.
She said: “We are preparing for a no deal because we don’t know what the outcome of the negotiations is going to be.
“We are all focused – as Claire is and the whole Government is – on making sure we get a good deal from the EU.
“If we go into a no-deal situation, there would I believe – and others have said this – be some short-term disruption.
“What is important is that Government puts in place measures that make sure we can make a success of Brexit, regardless of the deal we get from the EU.”
Brexit news: Theresa May preparing her showpiece Conservative Party Conference speech
And after details of her plan for post-Brexit border controls were unveiled at the conference, the Prime Minister insisted she was still committed to bringing net annual migration down to “sustainable levels” in the “tens of thousands” rather than hundreds of thousands.
She added: “It will take time to get to where we want to and – as I’ve always said in the past in terms of dealing with immigration – you constantly have to be looking to make sure you’ve got the rules right and people aren’t abusing the system.
“So it will take time to get to those numbers but of course having the ability to bring control in relation to those people coming from the European Union will help in that process.”
In another interview, Mrs May rejected suggestions that the economic squeeze over the last decade was driving voters towards the hard-Left agenda of Mr Corbyn.
“No, what I did when I became Prime Minister was recognise the concerns of people in this country – concerns from some people that globalisation had left them behind,” she said.
Brexit news: Theresa May will deliver a showpiece speech tomorrow
“In recognising those concerns and addressing some of those concerns, it’s important that we also recognise that it’s free markets, it’s capitalism, it’s open economies, trade around the world that have brought many of the great developments in human life.
“We also need to make sure that it works for everyone. That’s why I’ve said I’m working for a country that works for everyone.”
She added that the Government will soon publish fresh proposals for solving the Brexit row over the Northern Irish border.
“We are continuing to work on that new offer and we will put a new offer before the European Commission,” she said.
She added: “We are working on the proposal that we will put forward to the European Union on this so-called backstop.
“People use this phrase ‘backstop’. What it means is a guarantee to the people of Northern Ireland. We committed to that in December in the joint report.
“I did that because people of Northern Ireland are part of the United Kingdom. I think it’s important that we are able to deal with their needs and requirements as we do with people across the UK.
“This concept of introducing no changes in that regulatory environment without that consent of the people of Northern Ireland was in that December joint report.”