And frankly has some really badly worded, almost double negative, questions where you have to really concentrate on what they're asking!
OMG this is so true. Whoever wrote and signed off on that form needs to be taken to some sort of Campaign for plain English court and tried for crimes against the English language, grammar, logic and meaning.
We actually ended up with 4 UK passenger locator forms (make sure you create an account and can login back in and out before you start) because we got stuck in a Catch 22. You need your seat numbers for the 2 adults to put on your form i.e you need to have checked in and you can't check in (TUI) without the 2 X passenger locator form references! So I did 2 adult forms (kids on mine) which is about an hour's effort, used those to check in with TUI to get seat numbers, then went back and did a second version of the forms all over again where I didn't leave the seat number blank! Then I showed TUI the ver 1 forms at bag drop/check in (so same as what I put on the online check-in) without the seat numbers and was going to show ver 2 with the seat numbers at UK immigration, as I didn't want to be quarantined by test and trace if someone at the back of the plane (we were at front) tests positive on their day 2s, but they didn't ask for it (though can presumably see it on UK.gov?)
No idea if any of this is actually checked in the background! The UK form is way easier if you can have your seat numbers for return journey beforehand i.e pay for seating if you can. The TUI system wouldn't let us, even if we'd wanted to, as we were traveling with children and they want to control placement of them in the cabin, apparently, for covid.
Honestly, they whole thing was like some kind of beurocratic joke, with little basis in science or reality. We had another short trip planned and have now cancelled it as it really is too much hassle for a large family on a short trip.