We took DAD to HKG last month on an Avios booking - we arrived in DAD by car from Hue. Flight was an all economy A320. The lounge at DAD was nothing to write home about. Dreadful coffee and very little food. The flight it self was fine - I think we got a small breakfast with some fresh fruit in a little pot. Arrival in HKG was into a satellite terminal, from where we had to take a bus to the main terminal.

Funnily the BA site did not recognise DAD as a valid airport code, and insisted we would be flying from somewhere called 'Null'

I do concur with the OP regarding the boarding at C gates in LHR for the A380 flight. It was a total shambles.