Passing through a UK airport while on the way to another country is called ‘transiting’. Some travellers call it a ‘layover’.
There are 2 types of transiting:
‘airside’ - you do not pass through UK border control before you leave on your connecting journey
‘landside’ - you do pass through UK border control, but come back through it and leave the UK within a short amount of time (usually 24 hours)
Find out if you need a UK visa for your layover.
Coronavirus (COVID-19) travel rules
You do not need to take any COVID-19 tests or fill in a passenger locator form if you transit through the UK. This applies whether you are fully vaccinated or not.
The country you’re travelling to from the UK might still have COVID-19 entry rules in place. Check the rules for the country you’re travelling to before you go.