Managed to get hold of a PCV valve today and successfully changed it, took about 15 minutes. Cleared fault codes and went for a spin - fault cleared and massive difference, the car must have been running really badly before. The valve unit is the 'N' variant (06F 129 101N) and cost £38 incl VAT, the one I took off was F variant. Anyway I am happy to have been able to sort it quite cheaply. Thanks for guidance!
Russ