Set the thermostat at 19°c, costs rise by 8% for every 1°C increase.
Try not to heat rooms which are not being used. Set lower temperatures in rooms where there is physical work and reduce heating at the weekends. Installing a controlled heating system can also reduce costs as specific temperatures can be set in certain rooms at certain times.
In my experience people have a lack of understanding about heating. Heating needs to be set up correctly a substantial amount of money can be saved by just understanding and maintaining your heating properly.
Many people have their boilers serviced but neglect their heating system.
It can be difficult to choose the right heating system for you and the best way is not always the cheapest way so many people make this mistake.