You can park at the Mac Arthur Glen car park to the back of the centre or the multi storey.It's about £3 for 2 hours
Or there's the asda car park. It's a longer walk and 50p for 3 hours.
Or there's a car park at Toni Macaroni at the roundabout that's free and west Lothian college right next to macaronis and a 5 min walk.