The only sets that are available are from Autostyle and are the footwell mats and the parcel shelf. Coverdale will sell you about 9 metres of carpet (plus you'l need undelay) to do the rest but do not have a template for the whole car.
My S2 carpets were redone in 2002 by a company called 'Touch of Class Upholstery'. They are in South Wales and the number is +44 1443 875874...worth a try
If anyone knows a good priced specialist for the repair of seats in Kent or SE I would also like details. I was told Cass Brothers in Bromley, Kent, are good. Anyone know them? They apparently do carpet and upholstery repair/replacement.