I have looked at a few different recipes to make the chocolate paste using chocolate and either liquid glucose or golden syrup, I am finding that it is quite gritty and not smooth, any ideas?
What I've discovered when making modelling chocolate is that if you don't stir fast enough some of the chocolate will start to solidify, making small lumps in the modelling chocolate. I always ask someone to pour in the syrup whilst I stir, that helped me. Also, for some reason white chocolate is harder to make, and it's therefore (my opinion) that you really need an extra pair of hands.
And as an "answer" to chezzabelle, I always mix my modelling chocolate with some fondant if I want to cover a cake with it. Modelling chocolate doesn't have the same elasticity as fondant so it tears more easily. So it was the chocolate's fault, not yours ;)
I find that the modeling chocolate will be a bit gritty until it completly sets. after that, kneading a few pieces at a time will smooth it out.