Booking plugin

Im looking for a free or paid booking system that can operate as follows:

Would like a form on our site that I can make a custom form with details such as voucher number etc. They look for availability (booking system needs to work in hours) and book in. Email comes to us and we approve/disprove and confirmation email goes to the customer.

Backend for staff to log into and make/amend bookings.

Multiple resources, so in our case its different pilots with different aircraft.

Cheers

http://www.goflyoxford.co.uk