Do a home energy check at www.energysavingtrust.org.uk. You could save up to £250 a year on bills.
Did this - having got cavity wall insulation last year, and the new efficient gas system, I reckon we're not too bad. We definitely need to get loft insulation, and we could probably replace a few more lightbulbs with energy saving ones.
I'm still awaiting my results, which are coming via email - when they turn up I'll let you know if there's anything to report.