For anyone browsing Malachain, here is a clear starting point on the subject.
Most heat leaves an ordinary home through draughts, thin curtains and an uninsulated loft, and all three are cheap to fix. Draught strips around doors and windows, a brush on the letterbox and thick curtains closed at dusk make a noticeable difference in a weekend. Topping up loft insulation to the recommended depth pays for itself within a few winters.
Set the heating to come on only when people are home and lower the thermostat by a single degree; the comfort difference is small and the saving is not. Bleed radiators, keep furniture clear of them and use a thermostatic valve to turn down rooms you rarely use. A smart meter or a plug-in monitor shows which habits really cost money, which is the fastest way to change them.
If you try any of these ideas, start small and adjust them to your own situation. What works for one person will not suit everyone, and it is fine to keep only the parts that help. Writing down what you changed, and what happened, makes it much easier to see after a few weeks whether the effort was worthwhile.
The most useful step is usually the first one. Pick a single suggestion, try it for a couple of weeks, and then decide whether it is worth keeping. Small, steady improvements last longer than ambitious plans that are hard to maintain once everyday life gets busy again.
It also helps to talk the subject through with friends or colleagues who have tried something similar. Their experience points out the details that guides leave out: how long things really take, which costs were unexpected, and which shortcuts turned out to be a mistake.