The car is my MK2 1.3 Golf Ryder...........

There's a really loud sort of grinding noise coming from what sounds like the gearbox when I ease of, it's one of them noises that makes you cringe and think "oooo, that's not doing any good!!!".
As soon as I put the clutch down, or accelerate again it stops. I'm pretty sure it's something to do with the clutch if it stops when I put the clutch down, but I'm ending up riding the clutch most of the time to stop the noise which is a) not doing the clutch in general any good and will more than likely make the problem worse and b) is dangerous, especially down hills as it speeds the car up slightly, meaning I'm using the brakes more too......
Any ideas? Thinking someone on here might have had a simlar problem.