I must be very late to the party, so I’m sorry but I haven’t seen this post so far. If you want to do the photo op, the staff will tell you the actual rules about hugging and touching and if you ask me, there are no other rules than the ones you create for yourself. Do or ask what you feel comfortable with, keep the word “decency” in mind and most of all, enjoy yourself. I can tell you that before you meet them, you’ll make every possible scenario in your mind and once in front of them you’ll be 100 times less brave than you had imagined anyway.
David, and Gillian in particular, have decades of cons behind them so I’m pretty sure they’ve experienced the worst and the best fans’ behavior already. I’m sure Gillian is ready to sign hundreds of vibrators already, so really, except if you’ve decided to be an asshole and do something really cringeworthy on purpose, I’m sure it’ll be fine 🙂