Check before you go to Cosford. I went there on especially from Aberdeen. After I had paid my entrance fee I was informed that the Battle of Britain area was unavailable because it had been rented out for a corporate lunch.
This must have been a while back as admission is now without charge, although you will be paying for parking from 01 Aug.
However I too have visited when Hangar 1 has been closed due to some corporate bash. Surely public access should take precedence over private events. Rent it out by all means but the event and preparation for it should take place while the museum is closed.
Planemike