@
TBox
You'll immediately see from the above that we're all different.
My computation is that i used 2,750 kwh in January. My cooking and heating is gas fired through a 36 year old boiler, which isn't the most efficient! (however its not cost effective to change!). My temperatures vary through the day from 19 to 21, and 17 overnight. We live in an extended 3 bed semi in suburban London, and have full double glazing, cavity wall insulation and loft insulation.
Annually I'm at about 13,000 kWh per annum, and that's helped by a solar thermal panel that heats our hot water - particularly in summer.
I still think some accurate information is required and then some investigation if the results are still on the high side. You've got lots of tips to check through. Please keep us advised of your discoveries as they emerge, even if that means the situation is much better than you feared.