Largely as BatBoy says. I recommend two resellers of C & W as you can't get that direct, and a couple of further options as well, but rather not list them just yet as I would just confuse you with too much information.
What sort of thing do you want the connection for? For example gaming, or huge downloading? Lots of social networking? Or just simple browsing, internet shopping, banking, email and so on?
The best for one of those may not be the best for the others.
Have you got email that doesn't depend on your ISP? If not, we need to think about that as well.
How long do you expect to stay there? That makes a huge difference to the landline costs/recommendation, as you have to have one, and then also to the broadband.