It will be awesome to add a calendar to the timetable, this is how i consider to be the best option.

When you define Days and Periods in the owl you should put a validity start date and end date.

The program could now generate a calendar for those dates which can be used to pin single events, define bank holidays where the school is closed or to see and publish the generated timetable in a calendar view.

This should not be a gigantic effort in terms of development but a massive improvement to the product.

Thank you