I had my Altea XL TDI in for service and have been pointing out to them at the last couple of services a noise coming from the clutch at low speed when on full lock. They couldn't replicate the noise but when I collected the car today, it was making the noise, and the mechanic experienced it also.
Car is 3 years old in 2 weeks thus I am determined to get this fixed under warranty.
Mechanic has suggested that the noise is pointing to possible DMF but they need the car booked in for 2 days and need to remove the gearbox first.
I will keep you posted..
If that's the case(knocking on full lock) I'd be checking the cv joints first, not the flywheel.