Sorry to hear your troubles. Maybe my story can be useful to you, since its very similar.
I had a 2009 Clubman (diesel engine) with premature clutch failure (clutch went at 56,000km). The story is here (with photos): http://www.mini2.com/forum/mini-club...seal-deal.html
Clutch was toast. I, too, was told it was due to my driving style. In the end, I wrote to Mini corporate (a long, polite and microscopically detailed letter) and they refunded solely the dual mass flywheel (just over €500), although initially they refused to pay anything. Total cost of the repair for me was €2300. I had to cover full labour costs.
Ah, right. Almost forgot - does that 2000 quote include a new flywheel? The reason is that, as you can see from my photos - a ruined clutch will also ruin the flywheel. Since your "S" model also has a dual mass flywheel, it cannot be resurfaced and therefore has to be replaced.
I wrote the letter in mid-December 2011 and, although they called me and said they would reimburse me, I'm still waiting for the bank transfer.
Sounds to me like your 2000 pounds quote is pretty consistent for work done at the dealership.
Count on them having the car for two full days (reason being is that they have to disassemble the front of the car and bring the engine out to access the transmission). If possible, try to negotiate a 10% discount on labour and parts (I did and was successful) and/or a free loaner for the two days. I'm afraid that's probably about the best outcome you can expect. I spoke a long time with the rep from Mini corporate Munich when he called me and he said that clutches are strictly considered a "wear item" (and therefore not reimbursed).