When our tourists welcome in London again? When will stores open?

12th  April, under step two of lockdown easing, non-essential retail will reopen.

21st June, end of lockdown.

HOWEVER - it could all change if cases shoot up again.  As more people will be fully or partially vaccinated by then, hopefully cases will be low.

As for tourism - people living in the UK will probably be free to visit in June, but who knows for those from abroad.  It all depends on their countries and whether a "covid passport" will be required.  It is all up in the air at the moment.

By midsummer - and even that is not guaranteed.

Non-essential shops open in April. Tourists won't be welcome until the end of June (ie when the current lockdown is due to lift); the requirements for entry (quarantine, vaccines, testing etc) have yet to be confirmed that far ahead.