Have a look at Bulldog (www.bulldogdsl.com)

I don't know if they cover everywhere, but they are way better than anyone else I've tried.

Also have a look at www.asdlguide.org.uk for info

And get yourself an adsl router modem (perhaps a wireless one) rather than faffing with the USB thing Freeserve will give you. Then you can just plug anything into the router and it will instantly be connected to the internet.