Here is all the advice you really need if you're a fellow teetotal person:
Nobody is going to notice !!!
Seriously, honestly and based on personal experience - you will be fine!
I know that Uni (fresher's week especially) gets portrayed as a kind of booze-soaked orgy with occasional breaks to attend lectures in a dishevelled and hungover state, but the only part of this that's in any way compulsory is the lectures!
There were a number of events last fresher's week (and afterwards) that weren't exactly my sort of thing - dubstep and r&b nights, pub crawls, cocktail nights, traffic light parties (which *terrify* me, even now!) so I didn't go. This isn't a stubborn refusal to try new things - I just saw things elsewhere that interested me more! I went out in town, went to see bands that sounded more like my sort of thing, had nights out in nearby cities (Derby and Leicester are both easy to get to from Nottingham) and went to less drink-centric uni events like campus tours (very useful!).
So what about the rest of the year? If you're a non-drinker, you're not confined to spend every evening locked away in your room or stuck in the library (although both of these are a good idea now and then to get some actual work done!) I love exploring the local area - on foot or by bus. It might be finding someone who knows the area a little better to show you interesting things nearby, or there's always the internet if you're surrounded by other new people!
You don't have to *only* go to uni-run events either - after your lectures, you're free to go where you like! I'm a big music fan, so looking up local gigs seemed a logical place to start! As much as I like my uni-mates, I've found it useful to have some local non-uni mates as well. Even if the people on your course are great fun, it's nice to have some variety so you're not with the same people all day and all night!
But what if people try to talk me into drinking?
Easy. Say "no thanks!". If they continue to put pressure on you - walk away. You don't have to do anything you don't want to, and if people can't respect that, they don't sound like great people to be hanging around with. Universities are rarely short of people - you can make other (better!) friends elsewhere.
Since being at uni, nobody has so much as questioned why I don't drink - it's not a big deal! They have their drink and I have mine - the conversation carries on regardless of what happens to be in my glass!