Bring some snacks. I flew LHR-HND and back last month, meals are ok but there is a long gap in between. Particularly on the way back, the flight was very long about 15 hours and they served the first meal immediately after departure and the second about 60 minutes to landing, leaving over 12 hours in between flights. No mid flight ice cream and constant queue of people going back to the galley to get a snack; they only served water or orange juice three or four times over the 12 hours.