Hi Mat
There is an interesting post in the thread underneath yours about how to access and replace the battery on a Q7.
As for coding, it would be necessary to recode the battery to the vehicle so that the system knows the capacity and voltage levels, etc for the alternator loading.
If you are taking the vehicle into a battery replacement centre then they should be able to carry out this coding, but check first.
Let us know how you get on with it
Cheers Trevor