yeah sounds like the master or slave leaking and losing pressure. also avoid sitting at lights with clutch depressed this wears on the realease springs.better to take it out of gear.

I took off my window wiper motor and sprayed fisholene in the cavity below the windscreen, then realised the fan pulls air from here for heater!! didnt use heater for three days!! but now i know it wont rust around the inlets like so many older cars do and leak water in!!