"How would you say "Mother this is my fiance Bill" (ive been taking french for the last two years but it doesnt seem t have gotton thruogh to me."

I think it would work if you said this: "Maman, voici mon fiancé Bill."
Another option would be: "Maman, je te présente mon fiancé Bill."

It's a bit more formal, which could work if Fleur's mother is a bit old-fashioned.