Got back from a 24 hour one 2 weeks ago ( 10 hours Rome to NY, then NY Raleigh, then another 3 hour car trip.)
It is no picnickfor sure. I was reading Magazines . Can't sleep on the plane .
Probably should do what a lot of them say, take a pill.
My next transatlantic will be coming back on a ship for sure. Just don't fret about it and think about London and your cruise back.