Porsche: How long before my clutch fails ?

It's not the RMS problem.. but a newspaper under the rear axel
yesterday and today it was as dry as before.. I had a mecanic drive it
and he confirmed my suspicion..

It's the clutch discs.. that are broken...
They had to take out the transmission to se properly what pieces to
order..

I need to drive the car 800 km friday.. So they'll take a look at it
next week.. But they would not guarentee the clutch lasting 800km...
The car drives just fine.. but pushing the trottle abit more than
gentle you feel the clutch is slipping...

I assume that driving gently, no hard acceleration the clutch slould
last me this trip ?

K