You may find the following websites useful (click on the bolded title to go directly to the website):
NCEA – information on NCEA from NZQA. This includes general information as well as the standards, examples of external exams from previous years of NCEA and assessment schedules.
StudyIt – general advice on HOW to study and specific assistance with NCEA English, Maths and Sciences.
TKI – internally assessed learning materials. Mainly for teachers
Jet Mag – how a bridging or foundation course could help you