The premier will tell Tories that she will pass legislation to transpose EU law onto the UK statute book when Brexit happens.
Mrs May again ruled out the prospect of an early election, insisting she wants stability for the country as she arrived for the gathering in Birmingham.
She told The Sunday Times: “We will introduce, in the next Queen’s Speech, a Great Repeal Bill that will remove the European Communities Act from the statute book.
“This marks the first stage in the UK becoming a sovereign and independent country once again.
“It will return power and authority to the elected institutions of our country. It means that the authority of EU law in Britain will end.”
Mrs May and Brexit Secretary David Davis will use the opening day of the conference to detail plans for the “Great Repeal Bill” that will allow Britain to “take back control” of its legislation.
The Bill will repeal the 1972 European Communities Act, which gives direct effect to all EU law, and at the same time convert Brussels regulations into domestic law.
This will give Parliament the power to unpick the laws it wants to keep, remove or amend at a later date, in a move that could be welcomed by MPs who are keen to have a say over the terms of Brexit.
The move is also designed to give certainty to businesses and protection for workers’ rights that are enshrined in EU law.
Mr Davis will say: “To those who are trying to frighten British workers, saying ‘when we leave, employment rights will be eroded’, I say firmly and unequivocally, ‘no they won’t’.”
The Bill is expected to be brought forward in the next parliamentary session (2017-18) and will not pre-empt the two-year process of leaving the EU, which begins when the Government triggers Article 50 of the Lisbon Treaty.
Mr Davis will tell the conference: “We will follow the process to leave the EU which is set out in Article 50.
“The Prime Minister has been clear that she won’t start the formal negotiations about our exit before the end of the year.
“As we prepare for those negotiations in Europe, we also need to prepare for the impact of Brexit on domestic law.
“It’s very simple. At the moment we leave, Britain must be back in control. And that means EU law must cease to apply.
“To ensure continuity, we will take a simple approach. EU law will be transposed into domestic law, wherever practical, on exit day.
“It will be for elected politicians here to make the changes to reflect the outcome of our negotiation and our exit.
“That is what people voted for: power and authority residing once again with the sovereign institutions of our own country.”
The repeal Bill will also end the primacy of EU law, meaning rulings by the European Court of Justice will stop applying to the UK once the legislation takes effect.
It will also include powers to make changes to the laws using secondary legislation as negotiations over the UK’s future relationship proceed, although more wide-ranging amendments or new laws may come forward in separate Bills.