Hi Mark,
I tried loading up the Ancient Warfare Mod (AW-1.1.045-beta-MC164.zip) with MinecraftEdu Build 14 and it seems to work pretty well so far. I haven't tested everything yet, but here is what I managed to do so far:
When I hold CONTROL key and right-click on a catapult I get the inventory GUI:
I load the ammo and click done to close the screen. I got into the catapult by right-clicking on it, then selected my ammo by pressing V:

I aimed the cannon by using the A & D keys and mouse, then pressed SPACE to fire:

At the moment I'm testing this mod on OSX Mavericks both client and server, but I can try it out on a Windows system if that's what your using.
Since your at the Legoland Discovery Center, I was wondering if you had tried the Billund mod? It was made by dan200 (creator of ComputerCraft) and adds "lego-like" blocks to Minecraft. :D
Good Luck,
Maize