Boris Johnson has played down suggestions there could be a “sudden big flood” of people heading back to work as he set out the Government’s “road map” for easing the coronavirus lockdown.

The Prime Minister said the measures – including encouraging those in England who were unable to work from home to return to their jobs – were “baby steps” as the spread of the virus eased.

However, the devolved administrations in Scotland, Wales and Northern Ireland pointedly refused to follow the lead of the Government at Westminster in dropping the “stay home” message in favour of “stay alert”.

Speaking at the daily No 10 press briefing, Mr Johnson acknowledged ministers were putting forward a more nuanced message, but said he believed the public would use their “common sense” as they entered the next phase.

“Everybody understood roughly what to do in the first phase and it’s by applying common sense that I think we will be successful in this second phase as well,” he said.

He added: “I don’t think any of us expect that tomorrow or for the rest of this week there is going to be a sudden big flood of people back to work.

“I think a lot of people will now start to think whether they fall into that category, whether they could think about going back to work.

“We are taking baby steps. We think that is the right way to do it. We have some leeway now.”

The changes, foreshadowed by the Prime Minister in his broadcast on Sunday, will also see garden centres reopen and people will be allowed outdoors for unlimited exercise in pursuits such as tennis, golf, lawn bowls and basketball.

However, they must keep two metres away from other people and only exercise with their own household.

Mr Johnson said people in England would also be encouraged to wear face coverings in enclosed places, such as in some shops and on public transport.

The chief medical officer for England, Professor Chris Whitty, said the changes reflected the fact that social distancing measures in some form would be required for an extended period.

“We recognise that we are going to have to do changes for a long period of time. Making things sustainable is extremely important,” he said.

Earlier, in the Commons, Mr Johnson said ministers would reimpose controls if the rate of transmission of the virus – the so-called R number – started to pick up again threatening an exponential rise in the number of cases.

“If the data goes the wrong way, if the alert level begins to rise, we will have no hesitation in putting on the brakes and delaying or reintroducing measures locally, regionally, or nationally.”

He added: “Our challenge is to find a way forward that preserves our hard-won gains, while easing the burden of lockdown, and I’ll be candid with the House this is a supremely difficult balance to strike.”

People can meet with a person from another household outdoors as long as social distancing is maintained. It can be one person one day and a different person the next.

Driving to destinations for outdoor walks and exercise is also permitted but fines for those who break the rules will rise to £100 in England.

The new document, which comes as the UK death toll neared 37,000, sets out future plans if the virus reproduction rate – the R value – can be kept below one.

These include:

– The Government’s Scientific Advisory Group for Emergencies (Sage) has been asked to look at the idea of a household “bubble” in the coming weeks, where one household is allowed to join up with and interact with one other household only;

– International travellers will be asked to quarantine for 14 days when they enter the country, either in accommodation of their choice or provided by the Government if there are no other options. The date of implementation has not been announced;

– The Government’s ambition is that all primary school children will be able to go to school for a month before the summer holidays;

– Non-essential retail such as clothes and shoe shops could be able to open no earlier than June 1 if it can be proven they can keep people safe;

– Pubs, bars, restaurants, nail salons, hairdressers, accommodation, gyms and cinemas will need to stay closed until at least July;

– The Government is examining “how to enable people to gather in slightly larger groups to better facilitate small weddings” from next month;

– Those who are currently shielding will be asked to continue doing so;

– Those who are not in the shielded group but who are more vulnerable to Covid-19, such as the over-70s, should “continue to take particular care to minimise contact with others outside their households, but do not need to be shielded”;

– Cultural and sporting events will be able to take place behind closed doors for broadcast from next month, thereby avoiding the risk of large-scale social contact;

– Playgrounds, outdoor gyms and ticketed outdoor leisure venues will remain closed for now;

The road map document also sets out how restrictions may be lifted and implemented on a regional basis, depending on local levels of infection.

The document says: “The Government may adjust restrictions in some regions before others: a greater risk in Cornwall should not lead to disproportionate restrictions in Newcastle if the risk is lower.”

An annex to the document says people are unlikely to get infected if they walk past somebody in the street, but they should avoid standing face to face with somebody where possible, with standing side to side offering a lower risk.

People are also urged to continue washing their hands regularly and to wash their clothes often if they work with people outside the home.

On schools, the document says approximately 2% of children are attending school in person, but says schools should urge vulnerable children and those of critical workers to attend.

The Government is also amending its guidance to clarify that paid childcare, for example nannies and childminders, can happen as long as good public health measures are adhered to. This could help more parents return to work.

Nurseries are expected to reopen no earlier than June 1 – at the same time as reception, year one and year six return to primary schools.

The report says the Government is hoping a vaccine or drug treatments will be developed against Covid-19, but says this cannot be relied upon and a vaccine may never be found.

It comes as the Government estimates that, as of May 9, some 136,000 people in England are currently infected with Covid-19.