I'm living in Dublin and for long time I had to order all food colorings etc. online BUT I found craft shop in Dublin. It's not big but they have quite few products in there. Worth to try- I already went there and bought black food coloring and lustre spray . It's near Grafton Street.
Go to their web http://www.kitchencomplements.ie to check map how to get there, buy online or contact them.
Hope it helps some of you