You could try taking the clutch slave off but leave the line attached (if possible can't remember). That would tell you if it is the clutch or the slave.
Yes that's part of the way you would do it. Basically start at one end, either the pedal or the clutch. Let's say you do unbolt the clutch slave to see if it moves and it does, then check the cast iron lever on the transmission and see how far that moves, work your way back. But maybe first check to see if for some reason the extension rod from the clutch master to the pedal is not bent or binding.
Good luck.
Aaron
.