British Prime Minister Boris Johnson on Monday confirmed pubs and restaurants could reopen to serve outdoors in a week's time, as Covid restrictions are lifted, but sounded a note of caution on international travel resuming.

Speaking at a televised press conference, Johnson said criteria for moving forward with a second phase of easing coronavirus restrictions in England had been met.

From April 12, non-essential retail, gyms, hairdressers and outdoor hospitality will reopen in England, Johnson confirmed.

"I will be going to the pub myself and cautiously but irreversibly raising a pint of beer to my lips," joked the prime minister, who emphasised caution when he first unveiled the plans in February.

"We think that these changes are fully justified by the data," Johnson added, while warning against "complacency".

However the prime minister gave little information on the resumption of non-essential international travel from Britain despite massive pent-up demand for summer holidays abroad.

Johnson said he was "hopeful" but would not commit to a tentative May 17 deadline to restart trips, saying Britain should not "underestimate the difficulties that we're seeing in some of the destination countries".

The government's Global Travel Task Force is to announce more detail on the UK's travel roadmap this week, after the UK unveiled a "traffic-light" system for testing or quarantine after travel to different nations over the weekend.

Currently people arriving in the UK from abroad are required to self-isolate for 10 days.

British nationals who arrive from a banned "red list" of high-risk countries face costly quarantine in government-approved hotels.

The government urged people not to book summer holidays, saying it was "too early to predict" which would be the green-lighted countries.

London has also announced it will allow a number of people to attend public events such as football matches from this month in trials of a virus certification system.

"Virus passports"?

But Johnson refused to be drawn on whether Britain will issue "virus passports" for all international travel or as a blanket tool for attending events or accessing services, an idea backed by many tourism-dependent countries and airlines but opposed by more than 70 UK MPs.

The prime minister said there was "absolutely no question" of people being asked to provide Covid certification to go to shops or restaurants in seven days, but left the door open to vaccination passes being used for travel in future.

Passes were "something that all countries are looking at" and "I do think that's going to be part of the way people deal with it" Johnson said.

The UK has already given out more than 31 million first vaccine doses and over 5 million second doses, a pace that has far outstripped popular holiday destinations such as France.

This has boosted the public mood after more than 126,000 people died from the virus in the United Kingdom, the highest toll in Europe.

On Monday in Scotland, where the devolved government in Edinburgh has set its own coronavirus restrictions, hairdressers and some non-essential retail were allowed to reopen for the first time in four months.

In Glasgow, salon owner Anne Ferguson told AFP it was "fantastic" to return to work, adding that she was flooded with appointments.

"Getting into the space and making it come alive again. That's just a huge, huge thing. It's just been very strange," she said.

From Thursday, those living in England will be able to access two free rapid virus tests per week, a measure aimed at curbing symptom-free virus spread.

This will make such tests far more accessible than currently. "More cases will be detected, breaking chains of transmission and saving lives," the government said Monday.