I want to fly into the UK for 1 day (from the US, also I'm a UK citizen), and then leave for another country. Do I need to pay for the test which they require me to do before or on the second day and do I need to stay in the UK for 10 days?
EDIT: It says that I still need to book the tests, but will I be fined and imprisoned if I don't take them since I will be in another country?