I finally got round to replacing my PCV over christmas. I reset the engine management light and am now some 700 miles or so later and it hasn't returned. It used to come back after about 200 miles. I haven't had my usual rev issues on idle either, so everything points to it being fixed!!
Also the noise that VW told me was my clutch release bearing has gone too. I'm well chuffed with that!! A £30 part which took 5 minutes to fit has solved all the problems on my car

Obviously replacing just the clutch would have been more than 10 times the cost which VW were encouraging me to do!!!