If your school has a whole school calendar available it will be listed here, follow the steps below to add the calendar to your Outlook client.
In Outlook, click on the calendar button in the lower left.
Then in the ribbon at the top of Outlook, click Add Calendar > Open Shared Calendar...
Type the name of the calendar according to your school.
Arrow Vale: AVASchoolCalendar
Waseley Hills: WHH School Calendar
The calendar will then appear under Shared Calendars: