Boris Johnson has unveiled a "conditional plan" to reopen society, allowing people in England to spend more time outdoors from Wednesday.
The PM also said people who could not work from home should return to the workplace - but avoid public transport.
He said a new Covid Alert System with five levels would govern how quickly lockdown restrictions could be eased.
He hoped the next step "at the earliest by 1 June" would be for some primary pupils to return to school in England.
In an address to the nation, Mr Johnson said this stage would also involve reopening shops - but he cautioned this would only happen if supported by science.
The next step could see some hospitality businesses and other public places reopen - "if the numbers support it" - but not earlier than 1 July.
