Hi
I've been a fan of Gillian's for over 15 years and been to almost every event she's attended so I thought I might be able to provide some advice.
FHM Mag - she doesn't like this magazine shoot, she's commented a lot on it over the years but I really wouldn't worry about her refusing to sign it, she's signed plenty of them. When she goes to these events (and she's done several XF fan events in the USA in recent years) she's happy to sign anything that isn't some weird sexual manip! She's got a good sense of humour, we've joked about the XF p 0 rn parody with her, she's not going to hate you because you show her a copy of FHM!!
Refusing to sign XF stuff - she did refuse to sign for a few years after she left TXF and I think, understandably, she has refused to sign XF stuff at appearances for other projects - at the stagedoor of her plays or at other film premieres etc, but she signed everything and anything XF related at the recent USA events.
Personalisation - Gillian prefers to personalise the things she signs because it means they aren't going to be sold on ebay! I've seen her question people that didn't want things personalised before (not that she is likely to do that to you!). I'm not saying 100% she will personalise her signings, because I guess it's down to time constraints, but I think it's very likely she will ask people their names and if you ask her to personalise it I would be incredibly surprised if she didn't. She did refuse to write certain messages that she was requested to at other signings, but she will be polite about it and ask what you'd like her to write instead.