TransAtlantic travel at 20 weeks

Gloria
Hi all
My DH and I are flying home to Manchester Monday after Easter. Our flight there isn't too bad- Miami to Philly then to Manchester, longest leg is about 6 hours plus some.
But return flight is going to be about 11 hours from London to Miami on the day I am at 21 weeks. 
I am totally dreading it as I have a hard time laying down sleeping in one position in 3/4 hours increments (gotta go pee all the time)
I am wondering if compression socks helps, as well as prego friendly spanks to keep the blood traveling. I have been swelling a lot as it is. And it hurts my legs.
Any advise would be greatly appreciated. 
Thank you xxx