Terminal 5C should alleviate some of the problems but as far as i'm aware there was never enough capacity planned into T5 to cope with all of BAs needs.
I just find it incredible that these stands without jetties aren't better served and that aircraft regularly arrive without any coaches waiting or steps. I've been on several BA flights myself that have had to wait 15 or 20 minutes for steps to be put on. Clearly not acceptable.