Then log out of your NZ account by tapping on your apple id and choose sign out. Then sign in with a UK iTunes account (this is a must). Then download the iPlayer app from the UK App Store.
Once it is installed, sign out from your UK account and then sign back in with your NZ account. Finally turn iTunes Match on again (don't worry about redownloading your music as any cached music should still be there)
Whenever you need to access iPlayer, log into your VPN first before launching
I frequently change the location of the App Store by doing this:
1. Open App Store 2. Log out of the currently logged in account. 3. Log in to your UK account. 4. The App Store will tell you your account is only valid for use in the UK store, press ok and it will redirect you to the UK store.
To get back to NZ, simply log back in to your NZ account.