Seems like a decent place to point out that there are good savings to be had on heat pump running costs with a smart controller designed for heat pumps which can learn the dynamics of your building then preheat when tariffs are low or outdoor conditions are favourable.

I work for homely energy which has such an offering, but fwiw I genuinely think it's a good product. It's been studied by Salford uni in their energy house lab, so if anyone's interested maybe dig into that for a more neutral verdict.