[Rich Rice]

I don't know if it is available in the UK, but craft stores in USA sell a product called "Mod Podge", for decoupage. It is water soluble, and hardens clear. Once it has cured, you can spray any type of clear protective finish you want over it. It can be applied with a brush or sprayed (if you have a sprayer). You will want to seal it when you are finished, as it remains a bit tacky. I've used poly and nitro over it with good results. Nice to work with, and water cleanup. Good luck!