We've been there twice this week. Straight down the A3/A24 - it took us about an hour and fifteen and the boys loved it.
Check for tides. The tide was out this afternoon and we walked on the sand waaay out beyond the pier.
Parking is easy and there is a fab (and reasonable) fish and chip place on the seafront.
What's best, though - is that you can be home so quickly at the end of the day.