Whatever date the Spaniards choose to re-open, it's all a bit irrelevant really.
Speaking as a UK resident of working age who owns a property in Torrevieja, I can't justify a visit of any duration while Uncle Boris still has this ridiculous 14 day quarantine idea mulling about in his head. I (and probably most other working people in the UK) simply do not have the holiday entitlement to take an extra 2 weeks off work because I want to return to Spain to finish off painting the house that I started back in February.
I do hope that the Spanish can come to some sort of agreement like the French seem to have done.