I'm starting Uni this year and I'm 20 - what are people going to think?and
I'm 25 and want to live in halls - will they allow this? Will people think I'm weird?
Last year, that's pretty much what I was thinking too. When I started last year (and moved into halls) I was 25 and worried how I'd get along with everyone else. The simple answer is "pretty well".
Classes and Lectures
These are the easy bits. In lectures, there is usually a sea of people there and you're pretty much just a face in the crowd. Just sit down, shut up and pay attention! Similar thing in classes really - nobody is going to care how old you are because (if they have any sense) they'll be paying more attention to the class. In both cases I wasn't the oldest person there by a long shot. I know all courses will be different, but there were a number of older students in most lectures I went to and nobody paid any real attention to this.
Making friends/Social stuff
Again - not a big deal. The trick is to talk to any and everyone! Worried you'll have nothing in common with your coursemates? Well, you're all at uni - that's a good start! My uni mates are a mixture of people much younger than me and other mature students (my age and older) and they're all surprisingly similar once you get talking! The only time my age came up at any point was during a conversation about 21st birthday parties and I pointed out that mine was a few years ago. Their reaction? "Oh... cool. So anyway...." and that was it. The thing to remember is that it's only going to be a big deal if you make it one!
Another thing I've seen worrying my fellow mature students is the question of living in halls. Personally, I loved it so much I'm going back into halls this year. Yes, it can be a bit noisy, but most of the people there are fairly reasonable and will shut up if you ask! For me, halls are a massive help! They're close to where I need to be, so there's no massive commute every day (just a short bus ride or relaxing walk!) and they're catered which means no washing up! That frees up a LOT of extra time!
As for being the oldest in halls, that wasn't a problem for me. The halls I was in had people from all years (including a few postgrad students) so I wasn't the oldest and just kind of blended in and got on with it. I've heard that some halls try to group older/mature/postgrad students together in one part of the hall, away from younger students - but I couldn't advise on which halls do this (TSR is the place to ask though! Someone will know how to find out!)
If you think you might be the only older student in halls (unlikely, but possible!) I think all you can do is front it out. Don't make it in to an issue - nobody else is likely to. If you do end up with any hassle because of it, halls have staff who are there to sort these problems out - talk to them.
Whatever you do, don't let age get in the way if you want to go to university! So far, it's been the best decision I've made - I had a fantastic year and can't wait to start the next one. Based on my own experiences, I'd encourage anyone else who is considering it to go ahead and at least try uni - preferably by jumping in with both feet and not giving a damn what anyone else thinks of them for it!