Combine two UV textures into one?

I have been creating a character, and I have created the head and the body separately (in the hope that I can create multiple of each and match them). I unwrapped both meshes and created image textures for them.
I have joined the meshes together, and at the moment blender renders everything perfectly (the head with the head texture and the body with the body texture), however I was wondering if there were some way to get blender to combine the two textures into one so I could load the character up in Irrlicht.
Also I’ve noticed that if I try to bake the texture, when I next render, my figure has gone completely black.