Welcome to LZ.
You are likely to get more replies to that if you post in the defender section.
But as you are Cornish, my own opinion is that carpet is a mistake, it will hold water. A rubber mat with a sheet of soundproofing material under it in the footwells is better.
And I would just get the kit, the material is heavy, and quite good quality, and they are good at cutting it to accurate shapes and sizes.