www.assemblies.org.uk is a website that has been mentioned on a previous thread and i have just taken one called "just a little bit" from the "current" tab. It's fantastic, worked really well and i did it with the same age range too. All you need is a french stick (bread) it even gives you a prayer (i missed out the hymn, as i only had 15 mins too!) The little ones enjoyed it because it was visual and the older ones because they could get involved. Or if you do not fancy that one there are lots of others too. Have fun with it, good luck!