The problem is the UK wanting out of the Euopean court of justice in all areas, unfortunately all member EASA member states have the ECJ as the ultimate authority over the EASA activities.
It is difficult to see how the UK can be in EASA and not under the ECJ for aviation matters.
The question is does the UK stay under the ECJ for aviation or get out from under the EU completely ? If so would it not be better to throw in our lot with the FAA and join the worlds biggest aviation system ?