This is why you don't suborn your sovereignty
The tentacles of the EU are not so easily withdrawn, as the British are finding out. What irony that they are now undergoing precisely the same thing that the American colonies experienced ~250 years ago!
As blarman says, Sovereignty, once given up, is not easy to get back.
Prime Minister May proposes a bit of this and a bit of that, a typical politician's approach.
The solution of Theseus in cutting the Gordian knot comes mind.