Sorry to interfere in a Cabin Crew thread but as a "Nigel" who commutes from France via LGW to LHR ( still with me?) could I add:
National Express no longer offer staff discount on the LHR - LGW service. You can however buy a block of ten open single tickets for 99 STG
Journey from North Terminal to T4 takes at least 45 minutes, LGW to Central Area at least an hour...much more on a bad day. ALso allow plenty time to transfer to Compass Centre - hopefully it'll all be simpler/slicker when we report at T5.
There is no formal BA shuttle bus (unlike Virgin) however you can sometimes thumb a lift on the occasional BA buses shuttling crew beween the two bases...but don't rely on it. Once you're on line you'll often as not find someone on the crew who is driving in the LGW direction after the trip so you may be able to get a lift.
Re travelling in uniform - An absolute "No No" on Air France, but you can get away with disguising it( though that's contrary to BA rules so I couldn't possibly recommend it
). Yes, we do get discounted tickets with Air France. Uniforms not a problem on BA flights. I must admit I haven't seen the ruling about not putting uniform in hold baggage (VS-LHRCSA's comment) - that's a new one on me and if it exists it must be a Cabin Crew only rule...