The official calendar is the one in SchoolBase. To access it, login to SchoolBase and click on the calendar icon. You have different views, and you can set it anyway you like. Please use it in combination with room bookings in SchoolBase to know if a certain venue is accessible.
Login here: https://mis.europaschooluk.org/Logon?Dname=europa
From the schoolbase calendar, you can also create a feed that you can add to your personal calendar. Click on "manage feeds" on the top off the full calendar. Here you can create a timetable view and a calendar view, which you can import in for example your google calendar, so you have everything in one place. Click on the + sign before the calendar, and copy the link to add to your calendar, by clicking on the little arrow next to "other calendars" (see image below) and "add by URL". Paste the link in the URL box, and click on "add calendar". It will take a bit of time, but that is it. You can select different colors for your various calendars by clicking on the arrow next to it.