Clutch?

[Dizeee]

I am trying to work out if my clutch is on its way out - 2011 Toyota IQ with 47k on clock. It has the loud and horrible sounding vibration / chassis shake at certain rev points, normally when clutch is disengaged and revs are between 2.5 - 3.5k in gears 2 and 3. I know this is a common issue and that some report a clutch change removes this noise. Personally I can live with it.

Anyway recently I am getting some odd sensations in gears 2 and 3 just after the point that the clutch is fully disengaged. It is a forward and backwards wobble / oscillation which feels similar to how it would feel if  you were about to stall but obviously the car is moving at a static speed. It is consistently inconsistent and doesn't happen all the time, its extremely slight and faint and I suspect most driver would not pick up on it, however I am hyper sensitive and notice everything. Generally I am getting it at around 30 to 40mph as I apply and adjust throttle inputs to maintain the speed limit.

I have it booked in for a clutch change but wonder if I need to bother and whether I have misinterpreted the symptoms. If just left to get worse / go untreated, what could happen - can a clutch just suddenly fail and if so what happens then? I barely use the car so would be happy to leave it to chance, or if not advisable I will just carry on with the repair.