So after much searching i have found some stripey fabric that i can use for the stripey dress.
The black stripe is slightly lighter than i wanted, but it was the nicest black and white striped fabric i could find. The only other fabric i found was made from a cheapy stin polyester and would have looked terrible, so i plumped for this one. The stripes are each an inch wide, which i think it about right, and it is a cotton fabric but it still has a slight lustre. It has a subtle floral pattern woven into the fabric, almost like jacquard, that doesnt really show that much. I know the original costume didnt have this, but i think its alright to use, and it will creaet an interesting texture to the finished dress. It also doesnt really show up that much. so its fine.
Here is the fabric that i have gathered fro the riding jacket and stripey dress all together in the box;