£16 a day on gas and elec? Sounds like either a faulty stat or stat is set to high. I take it you have double glazing? 20c is on the high side for a stat setting.
Honestly the last time i was not in shorts was 2018 with that BFTE, one day i grant you i was in long trousers but still a milestone! No where close enough yet for a purchase of long trousers, suppose the little hairy legs aid the insulation!
Looking like we may actually get some decent late Autumn/ early Winter weather at last, fingers crossed no unwanted southerly influence makes its ugly head felt, last thing we need!
I get how you feel, i feel the same in the Summer when it nudging 30c for several days. Take one positive though, you can still get a good nights sleep in this weather