Our heating is on all the time in winter (air source heat pump) at 20°, to heat our small, two-bedroom terrace house.
It works out at approx. £180 a month over the year. We don't have gas, so that is for all our energy use.
We are quite careful, though, for instance not using the hot tap unless we are actually going to use the hot water.
In practice, this means that we now normally use the cold tap to wash our hands, as the hot water takes so long to reach the hot tap that we would have finished washing and drying our hands long before it got there - in other words, every time we washed our hands we were paying to heat water that was doing nothing more than heating the pipes.
That, plus using a small air fryer instead of the oven, has reduced our usage a huge amount.