Finally managed to get the update installed. Took absolutely ages all together after having to download the updates twice and needing three attempts to get the car to recognise the software due to some issue with the way files are download on Apple computers. Then despite 100% of the data being copied I got an error message and had to start the update in the car again. Thankfully it worked the second time.
I wasn't even going to bother with the update, it was only because I was in Scotland the other week on a relatively new road and the system thought I was driving through a field! Think I can live with that in future after all this hassle. VW really need to look at how they issue these updates though as it seems such a cumbersome way of doing it.