Originally Posted by
LHR/MEL/Europe FF
you will need to discuss this with the cabin crew. I know some people have had success in swapping seats, but it is at crew discretion. They may say no.
They may also put other limitations on the swap - for example, one time swap only. So you may take the seat in economy and not get the chance to move back.
No harm in asking the crew on the day how they can accommodate your wises, but there is no guarantee, and no 'right' (in the terms and conditions or anything) to swap once the plane leaves the gate.
It will also probably help you if the first cabin is relatively quiet. Do you know the loadings for that flight?
PS. I loved that flight on the A380. It's the longest single sector I've ever flown and to do it on that aircraft in J in a quiet cabin was fabulous.