British passport holder - in need of Visa whilst visiting NZ

I'm backpacking from July and have a tour organized for China running from October 29th to November 5th. I am unable to apply for it pre-traveling as the trip is longer then 3 months away (earliest application date August 6th). If I have all of my papers whilst with me in New Zealand (9th-21st September) can I obtain it via the express route? Or can you suggest a better way to do it? Could also visit embassy's in LA or Sydney)