"Public Health Locator Form
New arrivals will be required to provide UK officials with contact and travel information prior to arrival by completing the Public Health Locator Form. This form must be completed by each member of your traveling party. You cannot submit the form until 48 hours before you are due to arrive in the UK.
Individuals arriving in the UK from outside the current travel corridor (see below for each country’s rules) must self-isolate for 14 days and may be contacted to verify compliance. You will need to self-isolate if you visited or made a transit stop in a country or territory that is not on the travel corridor list in the 14 days before you arrive in the UK."
This might be helpful, but
This might be helpful, but you might want to look at the whole document:
https://uk.usembassy.gov/covid-19-coronavirus-information/
"Public Health Locator Form
New arrivals will be required to provide UK officials with contact and travel information prior to arrival by completing the Public Health Locator Form. This form must be completed by each member of your traveling party. You cannot submit the form until 48 hours before you are due to arrive in the UK.
Individuals arriving in the UK from outside the current travel corridor (see below for each country’s rules) must self-isolate for 14 days and may be contacted to verify compliance. You will need to self-isolate if you visited or made a transit stop in a country or territory that is not on the travel corridor list in the 14 days before you arrive in the UK."