Model Rocketry is the place for everyone to start young and old.  This is the 'putting green' of rocketry. It can be enjoyed as a beginner through to a 'pro' level of skill.  Low power model rocketry is the best place to learn about rocket stability and safety before moving onto larger rockets. You can expand your modeling skills to increasingly complex model rockets and designs including rocket gliders . There are thousands of model kits available world wide with popular models available through local suppliers. Model rocket motors start at 'A' power and go up to 'F' power. 'G' motors and above are classed as high power rockets in the New Zealand rocket safety code. Each increase in motor letter designation eg A to B doubles the power. 

NAR model rocket videos https://www.nar.org/model-rocket-info/

Apogee https://www.apogeerockets.com/Getting-Started-with-Rocket

Designing your own model rocket using the free Open Rocket Simulator is the best way to get started in rocketry as you will learn how to design a rocket that will fly high and land safely.  

For the lightest rockets you can purchase body tubes and nosecones from www.aerospaceeducation.co.nz.  Balsa wood for fins or nosecones is available from hardware stores and hobby shops. For a quick build you can 3d print nosecones and fin sets from www.thingiverse.com or design your own.  

As an NZRA member you can get help from club mentors to help you get started and gain level 1,2,3 high power certifications.