You need to find out if your local BT exchange is equipped for ADSL and if you are not too far away. This can be done by looking up the web site of a potential ISP as most of them have a database of dialing codes and postcodes, inputting the information will give a yes, no or will be available in the future answer.
My own ISP <A HREF="http://www.clara.net" TARGET="_blank">www.clara.net</A> offer ADSL but it is not cheap.
Stay away from BT Internet as they are rubbish I should know as I work for BT and can have their internet access free but have to pay someone else if I want a working service.