for my experience last year, get there as early as possible. Walk around the paddock before the crowds get there.
Plenty to be seen within the circuit and where the car park enters the circuit. Stay for the final race of the day in the dusk (then try finding your car in the dark) It is a great day out.
See if you can dress up in 50s or 60s cloth - quite easy really, if you wife has not thrown everything out.
