There are solutions but that means no flights in/out of the UK for 8-10 years.
In 8-10 months of no flights in/out of the UK most of the money earning parts of UK PLC will have disappeared.
The UK will make Albania look like paradise about 7-9 years before the CAA can start doing flights again.
So there is not practical solution to leaving EASA
Also the UK Leaving EASA will cause the EU a lot of problems like how are they going to handle the extra capacity when Heathrow is shut. I suspect the Irish will love it. Turn Shannon in to a major hub for Transatlantic.