Has anyone fitted A1 alloys to their Fabia without issues? Looking at possibly putting a set on, but just wanted to know if it was a straight forward swap.

They are the same fitment as in 5x100 so A1 Alloys go on a Fabia, you just need the appropriate tyres for the size of A1 alloys being used, 

you get them in 16, 17 & 18" and different width and offset.