My tip is always take the midnight flights out of HKG, eat in the lounge before you fly and go straight to sleep.The Cabin is not a good lounge, the Wing or Pier is far more nicer and better than Galleries in T5. From LHR to HKG I always take the early afternoon flight and eat on board, couple of drinks and then head down as in my mind its now night time in HKG. I always make sure I am not on a 747 now, all be it I have flown so many times in the old coffin class and normally bag the front of the upper deck and always sleep well. They will all be gone soon but worth checking your flight and aircraft type before booking. I have to say CX beats BA everytime with service in all departments and food is food, never had a bad meal in over 200 flights long haul with CX.