I believe the A380's will depart from the 'free Starbucks' satellite (C).

A10 is the main bus gate and I've only ever got that one on a day I was flying with someone who rarely flies and was hoping they'd be impressed with the BA experience

A4 is usually domestic bussing.

I believe there's also bussing capability from B sat, but I doubt they use that very often, maybe if there's a last minute gate change.