I'm currently in my 2nd year at Liverpool doing astrophysics, last year I was at York doing physics with astrophysics (the same after first year to all intents and purposes).
I wasn't totally unfamiliar to Liverpool, as my girlfriend lives here (one of the reasons I transferred) so it wasn't totally new to me, but I hadn't gone around on my own or anything, and I didn't know the uni or city very well. I adapted without a problem though, a little bit of exploring on my own and with my girlfriend has allowed me to know the city well now, and I've explored the uni on my own and got to know it all without a problem too.
I'm living with my girlfriend and family, so I can't really comment on accommodation, I was eligible for halls though, where everyone else would obviously be first year, but I personally wouldn't have wanted that, I didn't really fancy doing freshers again. I was looking at private halls as well, it would've been a similar scenario, with a slightly higher possibility of being with mature students or 2nd/3rd/4th years instead of freshers.
Meeting new people on my course was the hardest thing for me, I'm not terribly social though to be honest and it would probably be a lot easier for most people, I also wasn't really after a group of friends to go out with all the time, again because I'm not very social. I have a group of friends on my course though, I basically just introduced myself to someone who I heard was also on the astro course (most of everyone else is straight physics) and he introduced me to a couple of people. It also helped that one of my first semester modules involved a group working class thing where I could chat to these people some more. As long as you're social I don't imagine you should have too much of a problem, on the whole students are pretty nice people, just say hello and mention that you're new and you'll be introduced to some people and it'll take off from there.
Make sure you catch up on material that isn't covered in your first year but is on theirs though (if there is any). It'll really help you out, I didn't and when one or two things were mentioned, I didn't know what they were on about and had a brief panic before reading up on them.
EDIT: Neg for this? Really? Just sharing my experience of the process.