Data on energy prices are published by BERR in Quarterly Energy prices:
http://www.berr.gov.uk/energy/statistics/publications/prices/index.html
Domestic prices are available on a regional basis. Electricity prices for England and Wales are not available separately, as data are collected by public electricity supply (PES) area, and some of these areas straddle the England/Wales border. BERR does not publish average gas price data for Northern Ireland. Regional price data are not available for industrial consumers.
For 2007, average prices for gas and electricity for domestic consumers paying by standard credit in pence per kWh were as follows:
England and Wales Scotland Northern Ireland Wales Electricity 11.55 12.15 11.42 — Gas 3.07 3.04 — 2.97