Jonny,
GC350Z got the phone kit for his car although his is an Irish car. It may be a case of buying the kit he did and getting it installed. Whether it'll work in a JDm I'm not sure though. Drop GC350Z a PM.
Also PM MJP who is a trader in Nissan parts and will be able to get you the kit cheaper than a stealer.
Sat nav is useless, but you can use the screen with a uk sat nav, the rest of it is junk though.