@Charlie,
Since the UK buys more from the other EU countries than they buy from it and the UKs traditional trading partners were dumped by the EU there is absolutely no reason why the UK would be any worse off than it is today. In fact it would tent to be better off as an independent trader on the world market.
As a UK citizen living and working in Germany, if you don't have a UK address and you have been there for more than three years you don't get a vote!