UK ADSL comparator here >>>>
http://www.adslguide.org.uk/
Bit of information overload
My suggestion (for what its worth) avoid any service with download limits - there are several that don't have that restriction.
I think there is a BT facility on their web site to check ADSL "over the wires" availability in your area. Cable is a different option - but coverage might be an issue.
I am NOT an ADSL technical nor service expert but if you want to ask a few naive questions about the options either post or PM me. I am sure there are plenty of tech heads who can give more accurate info though.
Maybe also do a search on this forum for ADSL.
Good luck. I couldn't work on dial-up now. IMO more and more services and sites are assuming that 512k is standard connection speed.