The UK is consistently amongst the lowest household expenditure on food in the entire world. Only 3 countries in the world are self sufficient in food. If this "reasonable worst-case" scenario happens, surely the UK is one of the better placed to deal with it?

Most countries could easily adapt to other types of food. There are multiple source for carbs, fat and proteins, as well for various micronutrients. Some countries where obesity is rampant could also adapt to eating a lot less than they do now. That would bring the number from 3 (assuming that's true) to a lot more.

For only three countries to be self-sufficient, I suspect there is some funny definition like, "Well Americans eat 100pounds of pork each year, and they have to import pork to hit that number, ergo America is not food self sufficient." When instead you could switch calories to any number of alternatives.

> The UK is consistently amongst the lowest household expenditure on food in the entire world.

How?

> Only 3 countries in the world are self sufficient in food.

Surely a small island nation is not one of them?