Hi, thx for your quick reply.
At the moment I am integrating a schedule calendar from an outside source, but this is clumsy. The customer has to remember the sessions he has booked and then return to the cart to pay.
The sessions booking page I am using looks like this 'untitled.png'
It has a really neat layout, I am sure you could get something like this working, maybe in a popup or lightbox.
The layout comes from setmore.com
As to how you implement it, I have no idea. Maybe you could write a plugin to link to a setmore account? As long as the sessions booked reflect back to the value in the cart.
Regards. Joe