But wouldn't the dealer just have to replace the bearing? If there is life left in the clutch and it's working correctly, he could leave alone.

Correct, why should the dealer replace parts if there is life in them. BUT if the OP wants them replacing while its apart to ensure there are no issues down the line they could pay for new parts and get the fitted at the same time, should be no extra labout to pay while its in bits.

While I'd not buy car parts from eBay, as poor quality copy parts abound, the major part of the bill for doing the job on most cars is the labour.

So although the thrust race job should be covered, you'd be very foolish not to have a new clutch as all you would need to pay for is the parts. And perhaps 1/2 hour extra labour (to swap clutch pressure and driven plate over, and align the driven plate.

Exactly the same happened to me, and I actually told the dealer to bill me for a new clutch as well although they didn't mention it. .

Thanks for all the really useful advice, and thanks to my Dad for introducing me to Honest John! The dealer has agreed to fit a new Valeo thrust bearing for the car - all I am liable for is paying for the clutch. However I have spoken to the finance company which arranged the HP agreement (Barclays) and they have offered to pay 75% of this cost as a good will gesture, so I am left with a bill of £24.00 for a complete clutch kit, fully fitted.