This Booking module has developed into a really great plugin. It can be used as a Booking form for Courses on your site, or, by changing the settings of the activity, for booking face-to-face workshops for example.
There have been a few attempts at developing other similar event booking type plugins, but this seems to be the best in terms of features and updates.
This plugin makes it easy for managing participants and subscription of online and offline courses and events.
Email confirmations can be automatically sent to the manager of the booking instance, but it might be better to be able to enter an email address rather than username (this way the booking could even be monitored by someone external).
We've recently installed this on our public testing and development site (anyone can see this, even as a Guest!) so feel free to have a look and get a Teacher and Student experience of how this works for real http://plugins.moodlebites.com/