Quote from an .gov.uk site:
Coronavirus (COVID-19): how to self-isolate when you travel to the UK
When you arrive in the UK, you will not be allowed to leave the place where you’re staying for the first 14 days you’re in the UK (known as ‘self-isolating’) unless you’re arriving from an exempt country.
This is because it can take up to 14 days for coronavirus symptoms to appear. If you’re travelling to the UK for less than 14 days, you will be expected to self-isolate for the length of your stay.
From that I read that you can leave your location of self isolation to return home.
But you will not be allowed to leave your place of self isolation, not for exercise, not to get food and not to ‘walk the dog’. So it will only help you if all you need to do is inside one house and its garden and you do not need to go to a shop to buy anything while there or on your way there.
But you can ask friends (or shops) to deliver to your door or your garden.
Credit:stackoverflow.com‘