At Eastbourne we use S Grips on the front with Either Spice 24 or 28's on the rear. Ok it doesn't "look" quite right but never the less very effective.
On the carpet at Tonbridge (WKRCC) with a long straight I generally use S Grips all round and apply superglue to the outside tread on the front's if grip roll becomes a problem.
Sidcup being a short twisty layout I believe you can can away with the Spice or sweep tyres. As you probably know they are a smaller diameter than the Tamiya's and the difference to the top end on a long straight is quite noticable.
I have been experimenting the the new Tamiya 60d Type B slicks recently a they are very good on carpet. And the bit I like is the low wear rate.
