I'm rather surprised you couldn't even be bothered to read the very easy to find webpage:
http://www.airnz.co.uk/aboutus/caree...attendants.htm
Requirements
There is strong competition for relatively few vacancies, which may become available according to operational requirements. Unfortunately not all applicants will be interviewed. Applicants must meet the requirements as outlined below:
United Kingdom (UK) Residency
Only permanent UK residents will be considered (including those born outside the UK who have a valid work visa for the UK).
Passport
If successful with your application you will require a current passport. Airline crew are not permitted to operate on a Mainland China Passport.