I'm with PlusNet - changed to them a few months back and now have a 2Mb connection since my exchange has just been upgraded. Generally I've been very happy with them, and their customer service is the best I've seen - 24x7 local rate phone support (quite a wait, though, if you call at peak times) as well as a very good web portal where you can do most of the stuff you need to do.
They do "up to 2Mb" for £14.99, which means that you'll get it that fast if your exchange is up to it. Otherwise you'll get 512 Kb - but 15 quid isn't bad even for that. I pay a bit more (£21.99) since I need a static IP.
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They also do a referral system, so an existing member gets 50p off their sub per month for each new member they recommend. So if anyone does intend to sign up, I'd be very grateful if you used me as a referrer - PM me and I'll send you my PlusNet user name which you have to quote when you sign up.
It costs you nothing, and then you have the potential to get money off if you recruit new members yourself.
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