A calendar that customers can book sessions from. The current calendar lets them choose a session then just redirects to the product page where they have to click again to get the availability up.

Ideally, an interactive calendar would be customisable, with colours / images. Customers could view a week at a time and see all slots. When hovering over a slot they can then view more info (product page) or book the slot. I've attached a couple of mock ups from the timetable we use on our website. It would be useful to show sold out slots too, perhaps with a wait list option when hovering.