Thanks guys, I really appreciate the comments.
I did put some blue light on her back, but I couldn't get it to work so I deleted it and went to play with something else. As I'm working it, I think the image is starting to go a little flat so once I've got all the base colours in I think I'll revisit the lighting and shadows. Unfortunately I haven't had time to fire up the home PC lately let alone do any more work on it :(
http://infinatepixel.deviantart.com/