I've been digging into this today and thought it worth sharing. If you have a condensing combi gas boiler (it runs heating and hot water - no cylinder - and was fitted in the last 16 years) then there is every chance it is not running as efficiently as it should and making a small adjustment to the flow temperature can save a bit of money without any impact on your comfort.
There's a very good (and detailed) article on how to do this here but the key points that leapt out to me is that for 30 minutes of fiddling with the boiler the savings could be 8% of your heating bill (which is £120 each year) with little / no impact on comfort (yes your radiators will feel cooler but you leave them running a little longer to make sure you get the same amount of heat out of the system).
I know it's nowhere near enough to cover the huge increases in energy costs, but for anyone trying to cover all of the bases when it comes to being efficient, it's another trick in the toolbox. Could be useful?