Quick update. The dealer is still stringing me along about posting out a card claiming the last one must have been lost in the post. Latest is they have ordered a brand new card from Seat and will forward it to me allegedly next week. From the above, I know it will not work unless I make the DIY changes above, but at least I will have a card (if they actually send it). Will update mid next week but I’m not holding my breath!
I'd pop it in first just in case the car never had a card installed in it, in it's life then it will configure itself on that release. Then if that fails follow the instructions for lost and stolen cards and then the workaround for the latest update. I'd copy that card out to your PC as well before doing anything just in case it's the latest one to save downloading it again. 1520 is the latest one.