what kind of things do i have to do on the A8 in order to store it for the winter , so that i don't get fault code, or lights coming on in the dash?

 

Strange question, the car won't throw a fault code just because it has been sitting. Although anything with water/coolant in it is prone to rust if not driven for a long time, especially in cold weather! So either putting a heavy car cover over it or garaging it should be just fine.
If your not gonna start it for a while putting a fuel stabilizer in the tank should help the gas from deteriorating.

 

Thanks auditech79.

 

you might also consider putting it up on jack-stands, to avoid flat-spotting the tires from having the car resting in one spot for such a long time