B7 RS4, change gear clutch goes very light then doesn't seem to engage at all (pushing clutch down doesn't drop revs at all and can't select any gear).

After a while seems to return but then lots of juddering if I accelerate in any gear (including 6th at 60mph). Even worse when pulling away in 1st, impossible to do a smooth pull away plus lots of revs needed.

No slipping at all. Was driving completely normally prior to this, although did have a similar issue with clutch 3 weeks ago (pedal went 'limp' and couldn't select any gear, but this then rectified itself 5 minutes later and car has been fine since (no juddering on that occasion either).

Is my clutch shot?

It could be low fluid level - have you checked it?