I ended up buying the stuff and doing it myself.
I re-used the original seat cover as nothing is wrong with it.
Gel pad = £25 from Ebay
Staple gun = £9.99 from B&Q
the overhang on the sides cant be helped. I removed the foam all the way to the plastic on the sides and it still stuck out. At least it will be comfy though
The gel pad itself is very nice. So soft compared to the foam.
Think its turned out alright.