No, I did not use GM in my body butters. Once you add a liquid like water or milk, you are in need of a preservative, so I steered clear of that. You can certainly do it for youself though. I have a recipe that is very good and I would be happy to share it with you, however, I have to be at work in a while, so I would have to do that this evening when I have time to dig through my recipe books. Let me know if you would like it.
Soap making is not as hard as some people make it seem. When you consider that Sandy Maine from Sunfeather Soaps, made a basic trinity recipe and look how far she got. It does not have to be fancy to be good. I never bothered with actually superfatting my soap. When I make up a recipe, on the lye calculator I just use the 5% lye measurement and so the recipe is automatically superfatted at 5%. No need to add extra oils. Most of the time it is such a small amount that it makes little difference in the soap bar itself. When I am making up a recipe, I don't get too bothered with SAP values either. I just make sure I include something for hardness, for lather and so on and follow recommended amounts. Gets to be old hat after a while and honestly, I never notice that much difference in recipes that are good and so I narrowed mine down to 2. My regular 5 oil GM soaps and a castile GM soap.
And for what it is worth, most people in the handmade B&B biz think Lush is crap. Have you ever been to the Handmade Soapmakers Guild? I used to be a member and it is a good place to get insurance, which I assume you have if you are already selling. But it is a nice organization to belong to when you are selling soap. Lots of stuff to look at there as well.