Having logged into Outlook online (https://outlook.office365.com/) select the calendar icon from the bottom left.
In the left hand menu you'll find the option to import a calendar (below the small calendar)
You'll initially be offered popular public calendars.
From the left hand menu select 'From Web'.
Enter the URL from the calendar you wish to subscribe to and give it a meaningful name then click 'Import'
The calendar will appear in the left hand menu.
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.