Hi Dermy,
Wayne Sainty is your man.
Wayne re-coated my 16" primary and its secondary 9 years ago now.
These are still perfect (easily better than new because the original Meade coatings were rubbish.)
Get the "enhanced" coating, which is an additional protective layer of titanium.
This is worthwhile because it is extremely hard and it
increases the optical reflectivity beyond just aluminum coated with silicon.
Wayne can tell you how to pack your mirror for transport.
https://palmwayoptical.com/
Cheers
Geoff