BT Openreach have launched an official FTTC Availability Interactive checker

http://www.superfast-openreach.co.uk/where-and-when/

Its seems very accurate and a good judgement for what is available in your area and when it may be coming. Hopefully we should get confirmation in the coming weeks from BT Openreach that they will be increasing the allowed network spectrum to increase the maximum downstream speed to 80mbit and 20mbit upstream.