Querying a WFS endpoint like this only makes sense if you know your addresses are well-structured and match exactly what's available in that WFS. It's not a search endpoint.

You probably need a geocoding API. There are lots to choose from. In Python, geopy is an abstraction over several geocoding APIs. The one to pick will depend on things like how many addresses you have to geocode.

They will probably univesally supply coordinates back to you in latitude/longitude (WGS84 datum), which you will need to reproject to NZTM coordinates (i.e. convert ESPG:4326 to EPSG:2193). For this there is pyproj.