Hi I am very new to working with fondant and I have offered to make some cupcakes for my works summer fayre.  I want to make animal faces to go on the top,

I was wondering how far in advance can I make the individual pieces and what's the best way to store them so that I can still put them together and they will still be edible.

You can make fondant pieces ahead of time and stick them in the freezer. If you're putting them on cupcakes just take them out of the freezer and stick them on when they're still solid, and they'll soften up when they warm up. Freezing them prevents them from hardening up the way they would do at room temp.