Once you've done it a few times and got the routes sorted, get yourself in a twin and try it at night. On a good night it makes the day stuff look rather routine and the LHR crossing is much easier because their traffic volume is much lower. H3 is easy at night cos you fly from dark bit to dark bit but H10 is a bit of a bugger!
Enjoy the trip and make full use of all the very good advice that has been posted.