Multiple Calendar Entries for Office 365 Education

Hi

I am looking for a way to quickly add all the events for the next academic year to all Staff members of our Office 365 Education deployment.

I know I can add each entry individually, and invite members to attend, but I have about 150 events, including school holidays, inset days, weekly staff meetings, reporting deadlines, and wondered if I could upload a spreadsheet or something to make this a much quicker process, even in part?

Just adding the events to a Whole Staff calendar would be  a start ?

I hope someone has a suggestions

Thanks

Ieuan