A4 judder on first gear when driven 60 miles +

Hi to all Audi Owners

I recently bought an Audi A4 2.0 TDI with the extended warranty. I have recently noticed a problem with my car. After I have driven over 60miles +, noticed that my car slightly judders on first gear when I pull away. 

Took my car to Audi Southend with an appointment. Tech after carrying out a check came back saying that he could find no fault - reassured by the 'Expert' that clutch is in perfect order. 

I was told to come back when the fault recurs. As such deliberately drove around Essex to go over 60 miles to recreate fault - which I did. The same tech drove when I was seated with him and he told me that  he needs to carryout further diagnosis as he needs to remove the gearbox and clutch components to investigate further.

The guy from the services desk said "Once diagnosed, should the cause be a non-manufacturing defect i.e. clutch wear, the cost to rectify would be your responsibility. Should it be found to be a Warrantable defect, all costs to diagnose and repair would be waivered". 

Where do I stand? I am very frustrated as I have only had the car for 6months. It was mainly driven on motorways. Do I give the car to them with the above mentioned agreement? Very confused.... Any advice would be highly appreciated.....

Thanks In Advance... 

PS: He also stated that it would cost me about £1000 to get the clutch done.