hi ive got a 2.0 tdi its recently started juddering at when driving at low revs between about 1200 to 1700. the revs bounce up and down. revs out and drives fine above this does it bad when engine is cold and runs fine when up to temp. recently had the cambelt changed and has only done it since then. I took it back for him to check again but said it was probably the injectors and quoted me £900 to recondition the injectors .other than that he said he doesn't know. I did a full service on it with fuel filter but no difference any suggestions of what could be causing it would be greatly appreciated

I would check the throttle body. It doesn't take long to take off. Mine was doing something similar and found the throttle air intake valve had seized. It's quite common. Might not be but worth checking.