Local statistics on energy demand are on a web site and can be seen by the public. The data comes from the Department of Energy and Climate Change, and gives gas and electricity use for some parishes, including Thornbury, and other data for South Gloucestershire. The data can be seen on The Converging World energy hub. The latest data is for 2010.
You can also enter details of your house, and it will give you suggestions on how you can improve your energy efficiency. There's lots of other interesting energy stuff on the Converging World website. The web site is not entirely complete yet, so there may be hiccups.
The Converging World charity has built this energy hub website, using profits from building wind turbines in India.