I used to supervise one of the ticket booths at Farnborough while at uni and the amount of cars arriving did get a bit mental, although there was plenty of parking available. Some booths were alway much busier than others (not sure why – perhaps varying signposting?)
They used to do a free bus service from Farnborough station (I think) so that might be the easier bet if you are staying in Bracknell the night before? Only thing with that is that every bus used to be pretty full (although it was an almost constant stream) and you'd end up with long queues to buy a ticket as each bus unloaded.