Im on Gio-internet, they have a package that i use called home500 it's £18.99 a month (With a one off activation charge of £59.95).
You can use your own modem and filters or buy the whole package from them.
The only thing is it seems to not work one day every couple of months though..
and they dont answer emails, you have to phone them up.
But they are so cheap, i'll be sticking with them for a while yet.
http://www.gioadsl.co.uk/