My guess would be the release bearing as well Chris.

Mine makes a bit of noise when i'm idling and when i pull away it does rattle a bit, but if i put my foot down on the clutch the rumbling goes away if i then take my foot of the clutch it does knock a bit as the clutch engages, it sounds like a 'donk' if anything

As i'm writing this i'm thinking to myself that i should get the clutch changed asap!

hope it helps