Depends on what time your presentation is. If its before 6pm then drive to Falmer Village and the club have arranged parking in a field, just look out for the stewards, (its free by the way). If your presentation is after 6pm then you can park at the ground. An alternative is the Swan car park which I believe the landlord is happy about providing you pop in for a pint at the end.
Not sure about if you drive there from Woodingdean, but if you come off the A27 there is a sign at the side of the road just before the new lights directing you into the village.