I'm in lockdown in Spain. Very strict proper lockdown. For 6 weeks. NOT UK 'lockdown'.
I am interested on how you plan to get from the airport when I can't go to the local park/garden without risking 1,000 euro fine or sticking out like a sore thumb on the deserted streets.
Also, if I can't stay with relatives here, living 5 minutes away, how on earth is anyone thinking they can stay with relatives having just turned up from England?
Also, the Brits behaved so, so appallingly when lockdown happened here, you really WILL NOT be welcomed back any time soon.
My DD is not going back to school before September, this has been confirmed.
Why do you think you can turn up here and do things citizens have no right/chance of doing? Why do you think that would be accepted? 
Next month? Good news? Crazy.