Air New Zealand Air Points - Koru Club Access on JAL Codeshares

I wil be travelling Akl-Nrt-Lhr vv on a JAL ticket with the Akl-Nrt-Akl sectors operated under a codeshare by NZ. I am a Koru club member. Will I be able to access the Koru club in Akl or the lounge contracted to NZ in Nrt prior to Nrt-Akl?

No, it is a JAL ticketed itinerary.

The exceptions to that rule are only SQ New Zealand <-> SIN, and UA MEL <-> SYD <-> LAX. However these exceptions may be out of date.

You could of course still try before the NZ operated segments... no chance for the JAL operated segments.