It is basically never cold enough to die of cold in the UK. Winter death "surges" are just death by NHS. Anyway insulation is only worth bothering with if you give up on ventilation (excepting expensive heat-recovery mechanical ventilation very few people have in any country) which is far more important - being a bit chilly is easily fixed with tweed but lack of fresh air really fucks you up. Turn off the heat, open a bloody window and put a jacket on!
I for one am grateful the UK managed to keep loads of nice Victorian townhouses because the Luftwaffe weren't that great at their jobs. They're nice, proper high ceilings and woodwork.
I agree with you that the government energy subsidy we have now is appalling. Should be dumped immediately. I'm paying £15/mo less than I did before - this is the most stupid use of national debt ever devised, I would rather pay what energy actually costs than be forced to be complicit in this.