I've just booked a BKK-LHR return for next month, simple you might think, but jeez it was hard yakka; five calls over two days totalling nearly three hours, during which time one my first options became unavailable.
After several false starts I finally got BKK-HKG-LHR (CX) and LHR-KUL-BKK (MH) ticketed, with the long sectors in F.
Having said that, the final KUL-BKK sector has now disappeared from the itinerary. Yet another call had them assuring me that it's still OK, but i've emailed seeking written confirmation. Worst case, I'll just make my own way from KUL.
Pleasantly surprised though that the taxes only amounted to $219, I expected the UK APD alone would be much higher than that.