just an update on the issue with the headlight,after 3 weeks of trying various things i gave the car to an auto electrician who said the unit was not repairable so i bought a new headlight from motorfactors who i always use,it cost me 730 euro.audi wanted 1450 for same unit!! anyway ive it fitted now so all good again.
by the way,these are very hard to get in breakers here in eire and i tried a few in the uk too but appearantly this is a fairly common problem on the A5.Greg