Chat about Novel Coronavirus - 2019-nCoV - COVID-19

Just for confirmation rather than a random on the internet: From the gov site - https://www.gov.uk/guidance/coronavirus-covid-19-testing-for-people-travelling-to-england

If you are returning to the UK within 3 days, you can use the result of a COVID-19 test that you take in the UK before you travel. You must use a private test provider for the test and not an NHS test.

The service on which you will arrive back in the UK must set off for the UK within 3 days of when you took the test.

Having just filled in the EUPLF I think you'll need to put in an address, but if not staying overnight then where you are visiting I imagine.