One difficulty I had, not having been there before - I did a day trip, and was checked in for both sectors at LGW.
When I got to GIB for the return half, I naively took myself straight through security. It was then a bit of a detective job trying to work out where the lounge was that BA used (there was nobody to ask once airside) and how to get in through the code locked door (I piggybacked, eventually).
I know I should have stopped off at the check in desks anyway to ask. I'll do that next time at a "new" airport. But maybe something could be done to help the unwary.
The lounge itself was fine, though - I had no complaints.