ADSL or Cable?
In the UK there's two main choices of broadband - ADSL which is what you'll have on a BT telephone line, and Cable which is what you'll have on a Telewest or NTL cable line.
However, only 66% of the country is in a Broadband enabled area, and sometimes even if your town is enabled, you might be in an area which doesn't have the broadband enabled equipment serving your road.
To check if you can get ADSL in your area go to an ISP such as BT Openworld or Zen and enter your phone number in the availability checker. For cable users, you should check your postcode on the Cable providers Broadband Information website.
If you're not covered by either ADSL or Cable broadband, then all is not lost - there might be a local scheme providing an alternative service such as Wireless broadband, or you could register your interest in broadband via BT's demand tracking scheme.