What are my rights if I am denied access to the toilet or changing rooms that align with my gender identity?

There aren’t any explicit rules stating that a school must allow students to use a toilet that matches their gender identity or provide gender-neutral facilities.  

The Ministry of Education noted in its 2015 Sexuality Education guide that schools may consider reviewing options around toilet facilities to ensure students have choices of safe spaces, as toilets can be unsafe environments for students who do not conform to gender norms (the guide is available from http://health.tki.org.nz/Teaching-in-HPE/Policy-guidelines/Sexuality-education-a-guide-for-principals-boards-of-trustees-and-teachers).  

The Human Rights Commission has stated that in order to support transitioning students, students should have the choice of using a toilet that matches their gender identity. (https://www.hrc.co.nz/files/3914/2378/4856/TGI-Fact-Sheet-A.html).