Originally Posted by
F100
You’d not be allowed to isolate at their home. Technically, you’re not allowed to meet them and even outdoors it’s with one other person only for limited exercise.
The following is from gov.uk regarding isolating at someone else's home:
How to self-isolate in your accommodationYou should self-isolate in one place for the full self-isolation period, where you can have food and other necessities delivered.You must self-isolate at the address you provided on the passenger locator form.
This can include:- your own home
- staying with friends or family
- a hotel or other temporary accommodation
Meanwhile the lockdown rules state that "leaving home" is not permitted for social gatherings, unless to visit your support bubble / linked household.
My take on this is that the subject of "traveling from abroad into the UK to visit family" is not well covered in the current lockdown rules and is ambiguous at best. Until the lockdown ends or there is explicit legislation/guidance to deny entry to foreigners from non "red zone" countries for non essential purposes, questions like those asked by the OP are very much valid. Whether or not you as a foreigner can be stopped from exiting the country is questionable, and I think it's best to see the new rules formalized before making any guesses as to how that might go.