Public holidays, sporting fixtures and many other series of events are often published in iCalendar (ICS) format online. You can subscribe to these so they are shown directly in your FastMail calendar, and automatically updated if a new version is published.
We'll check that this is a link to a valid calendar file, then create the calendar and sync over the events.
You can then rename the calendar and set its color in the calendar list.
If you have links to other official government public holiday calendars, please let us know, and we'll update this page.
(Other states do not appear to publish an official ICS calendar of their public holidays).