Thought I'd try and put a bit more of a positive spin on things!!
You can park in both carparks(LHR and LGW), I find this a hell of a lot easier than missing a bus by 10 minutes and having to wait another hour for the next one when you're knackered after a flight but it's probably cheaper to use the bus!! As for weekends, it is completely random and I know it can be a bit of a pain but when your girlfriend can request, with a bit of tactical requesting, she should be able to get at least two weekends off a month (eg. requesting an LA on a Monday, should give her the weekends before and after off!) Also, if your weekends are that precious, she could always go on Vswap and do back to back trips for extra days off!
It's not perfect but I've worked for Virgin for nearly 5 years and me and my boyfriend have made it work-the best bit about it is that he comes away with me on trips a lot then it's like a mini holiday that I'm being paid for!! Just hang in there till the concessions kick in!!