The long flight went really well in terms of Lymphedema. The longest bit was nearly 11 hours. I did as my physiotherapist had advised, and was often up walking, kicking my bum etc., and in the bathroom I would do 15 deep squats every time. I also did a lot of deep breating as well as some pelvic floor exercises. The leg was hardly marked by the flight upon arrival, fantastic! Also the trip home went fine, same procedure as the outward journey.
Update: See my tips and exercises for flying with Lymphedema here.