I did the event safety planning for this:
SOPARA
It was, as can be seen a relatively small event at Old Sarum and was heavily supported by the very deep pockets of some extraordinarily generous individuals and corporate sponsors in support of the Parachute Regiment.
I'm not sure about the initial funding levels but they were 'very' substantial before the commit button was pressed.
If you want to get an overall picture of what will be required from an event safety perspective get in touch with the Emergency Planning Officer at your local council and he'll be able to give you a steer on what you'd need in place as far as CAA, HSE and licensing conditions are concerned.
Good luck