There are few natural resources left. Resourcefulness requires resources.
We have lots of natural resources, particularly the climate and land to grow our own crops and raise livestock and our fishing waters to catch fish. That puts us well ahead of lots of countries to start with that don't have either (or both) who really are reliant on imports for the fundamentals of life itself!
Not to mention coal, oil, gas, ores, etc underground that maybe currently aren't financially viable to extract plus wind, solar and wave power. We have lots of resources!
But, we still have the whole world to import from just like we've done for centuries and we still do today. And, despite what Remainers have us believe, we will still be able to import from Europe!
Yes, leaving the EU may well change some things, but life will still go on!