Hi Mike,
Had a similar problem with my 2001 TD4.
Kept losing pressure on the pedal so had it looked at. Garage said master and changed it. Six weeks later same again.
Garage then said slave (£600+) but if I kept the resevoir topped up I could delay the inevitable.
Eighteen months down the line and a few top ups later, bang, the pedal hits the floor and there is a two mile tail back on the A38 until the recovery truck came.
£709 at a garage twenty miles from home, hire car to fetch my daughter from uni in Sheffieldand no car for over Easter.
Moral of the story?
Get it done!!
In all fairness the garage did put a new clutch in why they where about it.
Cheers
Don (now officially skint!!!)