The UK Energy Security Plan does at least try to cover essential energy needs (food production, hospitals, defence, civil powers and authorities, etc) indefinitely from domestic supply.

The Defence Industrial Strategy does the same for essential manufacturing capabilities.

Raw material supply security is the purview of many government bodies, including MOD, BGS, and more.

> But at which point this becomes ridiculous?

Securing the food supply to your population, the absolute most basic of human needs along with the water and shelter, is the furthest thing from ridiculous.