I was booked on Jy to Aus but it was cancelled in June, I therefor went on my own trip, regarding the flight the thought is actually worse waiting for it to be the day. I dont know if you can with Jy E tickets, but I went on BA website 24 hrs before and booked an aisle seat as I did not want to be stuck in middle!!!, We were allowed to Get of in Singapore but it is only for a wander and toilet break!!!but was just so good to get out of the seat, wear comfy clothing, try to sleep as much as possible,take a good book and watch the films,it is an awfull flying time amount but I am so glad I done it the holiday to Aus and the people were fantastic.I hope you have a great time....I DID!!