Well, I emailed Seat UK and was quite surprised they phoned me back the next day. They confirmed my car was due a map update and I needed the SD card. They gave me a part number of "000051884S" and said it was £129.17 ex vat.
A bit expensive for just a map update...
Looks to be correct
http://www.seataccesoriescatalogue.net/en/producto.php?PK=3716&PK_CAR=19&CAT=1978
seems to relate to V7 thou listed as V5