This problem could be resolved by implementing the domestic policies of a near middle class lifestyle universal dividend and a 50% rebate to consumers of consumer and asset (housing) prices. That way Britain could rapidly re-industrialize without the need to worry about either price inflation or unemploymentet. Let exchange rates be as they may.
The EU’s problems are clearly financial and monetary, specifically the current dominating, monopolistic and destructive financial and monetary paradigm of Debt ONLY. Integrate a new paradigm of Direct and Reciprocal Monetary Gifting into the debt based money system with the above policies and not only will there be greatly increased economic democracy and generalized commercial agent profitability, but many attending trade problems will dissipate or disappear as well.
You wouldn’t even need Brexit. The EU can’t prevent such domestic policy changes as per above. Let Britain implement them and the rest of the EU and the world would see how beneficial they were to the domestic economy…and their populaces would demand the same.