Oh boy,
Thanks guys but I'm having a lot of trouble understanding this!
GKDantas, thanks for that link, but that tutorial went totally over my head at first but what I'm having a problem with is that I'm not actually using shading domains. All I'm doing is creating the bottle in the spline modeller, picking the side of the bottle and drawing a rectangular area where the label is and setting that area to the label image using the texture map. Is this the wrong way to do this - should I be doing this differently?

Homer