Carlton,
We have several fully laden 742's in and out of EGPF during the summer months doing the KSFB. No problems getting off of 23, only issue would the terrain when departing 05. However 05 operations aren't exactly a regular occurrence and I've no dout a 744 could manage it without too many problems.
It would be great to see Virgin operate out of GLA, and if as you say there are crews living in and around the area, it might make sense to try it with a couple of flights a week