Quote - When I view this image I immediately feel that the skin is a little darker than it should be (according to the highlights on the hair) and there seems to be a little too much green colouring in the skin.  The lighting on the hair suggests a yellowish/bright light, but the skin looks more like a heavily diffused nature type lighting.

 

It is still a fantastic render though

Ok, that makes sense. But there is little what we can do about these things. Each of the textures has been made under different light condition and will react differently on a new light source. This means that you have to modify skin or hair to match each other.