Just stumbled across this thread. I have the same issue on a Clubman D, but I think it has the same clutch setup as the S. Visciously difficult to drive smoothly, the clutch is basically "on" or "off" with no in between.
Thought it could be related to the hydraulics but had the clutch fluid drained and refilled with no change. Thinking now it's probably down inside the bell housing - something like the throw out bearing or something. Have learned to adapt, but I have to focus hard on pedal action when driving. Kind of inconvenient to say the least.