from the travel guide:
http://www.seagulls.co.uk/documents/travel-guide-aug15-with-changes229-3021752.pdf
Eastbound: Leave the A27 at the Hollingbury exit and
follow the signs for Coldean. At the roundabout take the
exit for Coldean and after one mile, turn left at the lights on
to the A270...
The only time I parked at Bridge you turn LEFT by the travellers rest at the bottom of the hill, then RIGHT at the next set of lights, coming in under the bridge.
This is the way I see cars coming in (and out) as I walk past each week.