(Edited version of yesterday's comment from Alan)
The UK is a global economy. Without globalism the UK is nothing and the best we can hope for is an agrarian society - think 1400's. Our society imports almost all of our manufactured goods. Even if we manufactured all our goods here, we still need imported minerals.
The UK used most of its minerals in the days of the empire. So where do we get the rare earth minerals to manufacture computers, magnets (wind turbines, tidal, wave, electric engines)? Where are our lithium reserves to make batteries? Where are our copper reserves for all things electrical? Where are our iron reserves to make... well almost everything? Where are our mercury reserves to make CFLs (LEDs require rare earths).
And even if we did somehow magically discover all the minerals we require, where is the energy to mine & refine them? Complete guesstimate - to manufacture all the goods key to our society AND mine and refine all the imaginary minerals would easily double the UK's current energy requirement, possibly triple.
The green answer is simple – just recycle. But that is so naive I don't know where to start. Yes, you can recycle glass easily enough, but we have plenty of silicon (sand). Yes we can recycle paper (to a point – the paper fibres degenerate).
Did they miss the history of 1600's ? The UK ran out of wood: coal saved our butts. Iron smelting almost collapsed with shortages of charcoal, before a smart Brit discovered you can convert coal into coke.
My notebook uses tiny amounts of rare earth minerals - so tiny in fact that the energy required to extract and purify them is astronomical (fighting against entropy). And I have not even touched on modern pharmaceuticals. Have you ever had to take antibiotics? Survived cancer? Sorry - you're dead in Clegg's world - modern chemistry requires all sorts of key catalysts, platinum for example. Had bones pinned together after a bad accident. Sorry, you're a cripple in Clegg's world.
If you plan for a future for your family, either leave the UK - or learn how to farm. Oh, and short the GBP: it is going to fall faster than a lead brick at 50,000 feet.
photo © Nick Drew 2011