I've lived in Kingston since I was about 4, so hopefully I can alleviate some of your concerns (although I can't really tell you anything about the uni, just the area).
IMHO, it's a really nice town. You get some rough types who frequent The Works nightclub (although apparently their Indie night is quite nice), and just like anywhere it has it's share of chav's but they are pretty harmless - I haven't had anyone 'start on me' there since I was about 14.
That all sounds rather negative really but in fact I think Kingston is just the opposite. It's got a really great shopping centre (The Bentalls Centre), an enormous pedestrianised area with more shops than you can shake a stick at. There is a big Cinema/Bowling alley/Restaurants complex, a LOT of pubs (and most are really nice) and a lot of places to go and eat (from cheap to, er, not so cheap). There's also the Thames River - which is really lovely to walk up and down. There are lots of pubs and restaurants along the river front, and also lots of rural/grassed areas to sit and have a picnic or something.
Depending on how rural a part of Wales you are from, you'll probably find most people a bit cold - but that's just 'the London way'. Don't expect people to smile at you and say good morning, and if you do that you'll probably get funny looks. But that's not to say people are out right rude.
Another good thing about Kingston - you can get ANYWHERE in London with ease. There are loads of buses going a multitude of places, a train station, and Surbiton is a short walk or shorter bus journey away which has an even better train station (much faster trains to central London and more links to elsewhere).
To be honest, I don't think there is much that you'd want to get or do that you couldn't do in Kingston. I hope you like it there!