In the built in calendar for Mac you are able to subscribe to the calendars for school.
From the 'File' menu select 'New Calendar Subscription' or by using the ⌥⌘S
Enter the URL in the box that appears
The calendar details should populate if you'd like to adjust them do so now.
(i) If you'd like to sync it to your iPad/iPhone you can change the 'Location' to iCloud.
URLS for the calendars; School holidays https://www.google.com/calendar/ical/b2jumj1sofabji658l92fpu2sc%40group.calendar.google.com/public/basic.ics Exams https://calendar.google.com/calendar/ical/4mu3qc4q4n7rbktm71dikj0gv4%40group.calendar.google.com/public/basic.ics Students https://www.google.com/calendar/ical/k059on1vfbe940jeu7cbss6j04%40group.calendar.google.com/public/basic.ics PE Fixtures https://firstname.lastname@example.org/07f23911d69143369d254bcfd47348131999844004345909896/calendar.ics Staff can request the Staff URL from the helpdesk.