I'm not convinced that calling a Jag dealer in the UK will work to get any but a UK disc (and maybe not for that!).
You can get the discs from the maker (navteq). Not cheap, but then the XKR isn't!!

There's an XK section here & by all means try on www.jaguarforum.co.uk in case an XK owner knows more.

I don't know about the electronics etc in the XK but the diagrams are likely here: http://www.captainjaguarscathouse.co..._Reference.htm

Which Aussie forum? How active is it?