This dataset includes NSW public school term dates and public holidays.
The Department of Education sets the term and school holiday dates for all NSW public schools: https://education.nsw.gov.au/public-schools/going-to-a-public-school/cal...
School development days occur at the beginning of Terms 1, 2 and 3 and the last two days of the school year. Check with your school, as schools may vary some of these dates.
NSW public holidays are available here: https://www.industrialrelations.nsw.gov.au/public-holidays/public-holida...
The data resources contain historic, current and future dates.
Local Public Holidays in NSW captures additional holiday dates for specific localities.