I moved to London two years ago - from Leicester, which is in the UK, but the rent prices are still very different in comparison. How much you pay depends quite a bit on which zone you want to be in - so basically, how close to central London. The cheapest areas tend to be in East London (check out Shoreditch and Dalston for example), but it's worth looking everywhere regardless, because you can find some really good deals. Just keep an eye on how good of a tube connection a place has if it's important to you. If you're on a budget, I'd say you're a lot better off looking for house shares or renting a room - that's what a lot of young people on a budget are doing and it can be very nice if you find a good place. For sites to look on - I found all of my options on Gumtree, but I've heard good things about Zoopla as well. Good luck!