People in England who cannot work from home are being encouraged to return to their workplaces on Wednesday .Unlimited exercise, meeting a friend at the park and moving house are also now allowed, under new rules
The UK economy contracted by 2% in the first three months of the year, official figures show.
Meanwhile, Commuters in London said social distancing was "next to impossible" on Wednesday as many made their first journeys to work since lockdown rules were eased in England.
Street works inspector Matt Hickson, 47, told the BBC that he saw "less than 10% of commuters wearing masks" on his London Underground journey today.
"People are taking liberties not only with their own health but with other people's," he said. "There could be a second wave of infections coming."
Mick Cash, general secretary of the Rail, Maritime and Transport (RMT) union, said reports of packed Tube trains on Wednesday show how "fraught with danger" the government's return to work message is.
The government said it would have to "take steps" if too many people used public transport, after England's lock-down guidelines were changed to encourage people to return to work if they cannot work from home.