Rowes near Truro are pretty good although you will be paying main dealer prices, what end of the county are you?
Castle motors near Liskeard may be able to point you in the right direction they shift some serious cars. Apart from that you will have to rely on word of mouth to find a decent independent near you, I have a good one near Bude.

 

Thanks. I am in the St Austell/Par area.

May have to just settle for Rowes...

 

I'm using Rowes Honda at Plymstock, and so far they've been fine.
I've just taken out a monthly direct debit service plan with them which reduces the cost of services and is price fixed for 5 years. It also gives free MOTs, and can be cancelled at any time on a pro-rata basis. Might be worth asking about that. It's also worth asking how many S2000s they look after as it indicates if they've got anyone who's familiar with the cars.
Whilst main dealer servicing is more expensive, I think that "full Honda service history" is a good thing when it comes to selling the car.
It seems there's a few good independent Honda specialists in the Midlands and the South East, but they're definitely lacking down here.