In the most populated regions of the UK it doesn't realistically go below -5c basically ever.
The average minimum temperature in the winter months in London is 3c above freezing.
The average minimum temperature in the winter months in London is 3c above freezing.
https://www.mylondon.news/weather/london-weather-coldest-nig...
But - other comments have noted, some backup generation capability that use less green resources should be acceptable for such rare contingencies.
Probably a good half of our homes have fireplaces and chimneys.
It's not cost effective for everyone to have a wood burner but if only a small percentage used them on the cold days we'd be fine.
People obsess a bit about pollution, as a response to rare events it's fine.