Originally Posted by DaveS

It depends on whether you can convince the check in staff for the first flight. They could be obstinate and just treat it as a flight to the UK only which is understandable as they could take the flack if you did not board the next flight. It would be wise to have a backup plan involving getting a cheap day 2 test and filling a PLF at the check in counter. I am assuming you will have a pre-departure test for your final destination. Also assuming you have the right to enter the UK. If it is the same airline for both flights, see if a sales office can do something to combine the bookings.