Don't bother mate! The RAF Nazi plod with nothing better to do than justify their sad assistance will get you. The last I heard even the staff that work there have a designated parking slot. If your in the wrong one, car band for life. It will get much worse when lynham moves over.....so im told!
From the Brize homepage, basically you have next to no chance!
Once you have applied for your flight, you need to decide how you are going to travel to RAF Brize Norton. Due to the limited number of personal parking spaces we advise that you either get unit transport, public transport or a hire car. If none of these options are available to you, you can pre-book a space in the Medium Term Passenger Car Park.
CLICK HERE FOR CAR PARK APPLICATION FORM
Once we have received your request we will send you confirmation either to inform you that you have a slot or that there are no slots available. If you are unsuccessful in obtaining a parking slot you must not bring your private vehicle on to the station. A new RAF Brize Norton station wide parking permit system is now in force. All station registered vehicles must also display a colour coded pass designating which areas they are allowed to be parked in. Any vehicles found to be illegally parked will be removed at the owners expense. If you have been allocated a slot, on arrival at the Main Gate Reception, you must produce this authorisation which will enable you to get a special car pass. You must park in the allocated numbered space and ensure that the car pass is visible. We recommend that you check in first, park your car and then catch the shuttle bus from the main gate to the Air Terminal.