Hey Thanks, but i managed to work it out. I didn't even know you could turn off IKs.. =S
I'll post this up for the benefit of other newbies... to show that it's not the end of the world when you happen to skin your character BEFORE adding blendshapes.
I knew about how blendshapes must have the same number of vertices as the original model.
So what I ended up just doing was saving a copy of the file, unbinding the head surface, deleting everything else but the surface and then importing this file into my current file.
It's also good to note that the imported file should be centre pivoted, i.e. at the same coordinate as the original model. I found that if the imported model was off the centre, the deformations screwed up for some reason.
Anyway, hope this helps!