I live in a new build and my biggest heating bill this winter was about above £60. I only have portable air con because I WFH and my giant 4K monitors heat up to +46 and just blast that heat into my face all day long. That’s awesome during the winter as I don’t have to heat my work room at all, but during the hottest days it becomes a problem. Other parts of the home don’t need air con at all. Was OK even during last year’s heatwave.