Sorry for the late response.
I finally got around to installing SIM card from 3. (£40 valid for 1 yr, 12Mb total?)
The audilink system works ok for installing new destinations set up via Google maps (only from destop version, not android) and it allows some satellite images from Google, but this is all hung around the Audi map installed.
The live traffic works well but only on the main roads. It doesn't have the Google maps level of detail.
I haven't used the audi web access much yet, but this seems to be quite useful if you don't have a smart phone.