Hi Simon, i have all clutch parts if you are stuck, the friction plates as Antar Mike says are readily available, but I have a couple of sets if you need one. Think i may have a intermediate plate as well, but would need to check?
Good advice to hold the pedal down, if mine is left more than a week its stuck, so we have been doing this for years now! If you forget.... a couple of weeks you can get away with by riding around banging the pedal and jumping on the brakes.. a couple of years!! forget it! engine out and replace!
Good Luck,
Pete