I was considering coating the affected areas with epoxy, flatting back with medium grit paper and then spraying. 

Wow, that was a thread revival

No, I didn't, as the UK Distributor (AOC resins) didn't seem keen on importing any at the time.

That said, feedback on it from reliable sources on here seemed to suggest that it wasn't quite the hoped-for answer after all

If you're looking for a good gloss coating with some added UV protection, then EC's GC50 really does work well. I use it a lot but you really need to invest in the cup gun set-up and spray it for best results.

I really like the ability to carry out minor surface repairs without fear of losing the gloss permanently and being able to use a good spray tack without fear of affecting the cosmetics also.