Howdy Richard Wilding,
Events Calendar PRO does not offer any ticketing features on its own. However, our ticketing plugins do. They integrates with a large variety of payment solutions, not just WooCommerce and Eventbrite. We have Easy Digital Downloads, Shopp, etc. The full list is on our products page.
That said, I think Eventbrite Tickets will suite your needs best. It does allow free tickets/events. It also supports attendee aproval and waitlists because Eventbrite does:
Approval: http://developer.eventbrite.com/doc/workflows/
Waitlist: http://help.eventbrite.com/customer/en_us/portal/articles/428739-waitlist-management
Please note, in order to get those features all you have to do is signup at Eventbrite.com. You would also want to Purchase Evenbrite Tickets from here. Install that one plugin to your WordPress and input your EB API key. You are good to go! If you want to purchase Events Calendar Pro as well you certainly can, but that is optional. If you do it will just add the additional PRO features and continute to work seamlessly with the ticketing plugin.
Please let me know if you have anymore questions. If not, would you mind marking this topic resolved? Thanks!
– Brook