As an admin, when you make a booking you get an extra tab, "Toistuva varaus"
You can select a number of weeks for which you would like the system to repeat (weekly) the reservation and the system will attempt the reservation and give back the availability and price for all the instances.
This functionality is enabled by default for admins and can be enabled for users as well via the "Muokkaa koulun tietoja" menu
Once made, the multiple bookings created via this feature become "independent" bookings and cancelling one of the bookings will not affect the rest
At this moment paying multiple bookings at once is not yet possible, this will be a feature candidate for the next update.