The last part of my post was a description of the current arrangements.
Not sure we do benefit from being in the EU at all.
Cost of membership fees - £billions per year plus the occasional £1.6 billion top-up
Costs of each trade transaction
Costs of implementing all their laws, directives, regulations
Costs of the bureaucrats we have to employ in Brussels and Strassbourg
Costs of the MEPs
Costs of the European Elections
Costs of attending all these EU working groups, policy units
Cost of our Commissioner and his outer office
Cost of all those UK EU staff in terms of salaries, subsistence, accommodation in Brussels and Strassbourg, for their partners and children, schools for their children, and health care abroad, pensions.....
Go to do one heck of a lot of trade to pay for all that.