Electric blankets are great. What isn't great is that you let the house get too cold and you get moisture build up which can lead to mould. Then it gets colder still and your pipes freeze and burst. Suddenly the ~£1000 you've saved on heating becomes ~£10,000 you need to pay out on flooding.

Just run the heating at a lower temperature say 16c, it isn't low enough to cause problems but still vastly cheaper than trying to run the whole house at 21-23c.

As for electric blankets/throw-overs then they are 100% efficient compared to a gas boiler that may be 90% but you also pay more for per unit consumed. They are still cheaper though because you are just warming yourself to a comfortable temperature and not the whole house.

Sure, that's a cheap and probably more efficient way of doing things if you spend the majority of your time in one or two places. That's not what this post is about. The head of Octopus energy reportedly stated that an electric blanket is an alternative to central heating. Which is dangerous.