Well, we have looooooads of societies which is great for the social side of things
You can pretty much guarantee that you'll find something you want to join! Although I'd recommend having a look at them online before you go (
http://www.yusu.org/societies) because the Freshers' Fair can be a bit crazy.
Another good thing in terms of socialising is that everything is close together - I live right at the edge of the campus, in Alcuin, but it still only takes me about five minutes to walk into the centre of campus (i.e. to the lake/Central Hall), so it's easy to meet up with people. The only colleges that are out of the centre a bit are Goodricke and Halifax, but even then it's only about a 15 minute walk to each of them
Afraid I can't offer much input on clubs/going out since I'm not really a fan, but the majority of people I know enjoy the nightlife in York, and if it's not enough then you can still make trips to Leeds for nights out
Accommodation varies quite a lot throughout the university... the best places to be are Goodricke, Alcuin (especially the new quad which is where I am, it's gorgeous
), and New Vanbrugh. Worst places are the old parts of James (aka Old Goodricke) and parts of Halifax. But in general, wherever you end up, you'll be happy!
Personally I love the atmosphere here ^_^ It's quite a small uni but I like that, it feels more cosy, kind of. It's easy to find your way around and you bump into people you know when you're wandering round campus. There's tons of stuff to do in terms of societies, and everyone I know is getting on well with people and not having any issues with not having friends! It's a fantastic place
Anything else you want to know? I'm quite happy to answer questions
Also...
I don't know about the ducks, but the geese invaded Alcuin and crapped all over our paths