I make a lemon drizzle cake that I sell on my market stall. I always make a gluten free one as I have a lot of customers who are gluten free. People say you can't really tell the difference. To me it tastes pretty much like a normal cake but I can sometimes detect a very slight powdery texture from the gluten free flour although it is a very good cake. 

A friend of a friend who has seen pictures on Instagram has ordered one. She isn't bothered about it being gluten free but I am slightly worried about making it gluten free as even thought it tastes good she might think it is nothing special as she won't know it's gluten free. I often make gluten free cakes by just taking my normal recipes and substituting in gluten free flour. This recipe is different though as it was taken from a gluten free recipe book so it seems that the recipe was created to be gluten free. This is the recipe.

240ml milk, 15ml oil, 2 eggs, 260g gluten free flour, 3 1/2 tsp baking powder, 3/8tsp xanthan gum, 250g sugar, 75g butter, zest of two lemons

I'm slightly hesitant about just using plain flour instead of the gluten free flour and obviously ommiting the xanthan gum as the high liquid content from the milk might be because it's meant to use gluten free flour.

Do you think it would work with plain flour or should I just give her the gluten free version