Thanks to all those who helped diagnose the dead coilpack on my A4. (I love this forum!!) Managed to get a replacement for Ł23 including next day delivery. Fortunately, it was the first one that was dead, as without vagcom I was just having to try one at a time.
Problem is now fixed, car is running nice and smoothly again, however the engine management light is now illuminated permanently. When I had the problem it flashed on and off, but now it's on all the time.
I'm guessing (hoping), it's just that the fault needs to be reset or something. It's due a service in the new year so not too worried, just be interested in your thoughts.