If you know the clutch is going and you're still driving it then the only thing AFAIK that it will be "damaging" further is the already dying clutch & possibly the flywheel face which imo you should change at the same time as your clutch anyway.
Definitely safe to use still imo with the only real danger being that the clutch will just go at some point leaving you stranded at the side of a road, ...more than likely on a hill in the middle of heavy traffic, whilst raining with nowhere safe to pull over just to take the pi**.
Be as sympathetic as you can with it until you get it booked in to be fixed as otherwise it will go much quicker (obviously). Good luck.