I have been offered a cheap late 90's TF that has been sat around for a year or so. The clutch was working when the seller first fired it up, but after a couple of small manouvers the clutch stopped working!? I know no other facts than this though!
From the few details your have, I would suspect a hydraulic seal has given up. Pennies for a seal or pounds for a new cylinder but either way, a lot easier than replacing the clutch!
Not had to replace a clutch yet in 240,000 MG-F miles (two cars), but regular use probably helps.
