To reply to my self, I think I'm now looking at the Pictorico PPF150, to give the cleanest finish, unless there are any recommendations for a high gloss, ultra smooth, rich non metallic...
Seems the only European suppliers (I can find) are pictorico.eu in Germany, which isn't too bad for shipping.
I'm still slightly confused about the longevity of the material - will be under a UV blocking ultragloss polyester laminate, and mounted to Aluminium.