I was quite worried about it when I first arrived, but to my very great surprise, no-one seems to have noticed!! I'm mutter mutter mumble lots older than the undergrads around me. I'm pretty tolerant of how other people choose to leave their lives eg bops, drunken parties etc, but I'm a bit of an old fossil myself socially. But then my MCR has a wide range of activities to choose from, some at the bop end of things, others more fossily and all extremely welcoming.
In truth, it seems to me that most people here have such a variety of different backgrounds, life stories etc that no-one cares about things as meaningless as age. Individuality seems to be very well accepted and age doesn't seem to be an issue at all.