http://www.camelotthemepark.co.uk/3429/ ... tions.aspx
The web site is pretty pants for public transport information. I had a quick look at the links they provide, but they're pretty useless.
I very much doubt there's a bus like there is for AT/Thorpe.
However, as I'm in a good mood, I've done some planning for you!
This web site is brill for public transport: http://www.traveline.org.uk/index.htm (I suggest anybody unlucky enough to use public transport saves it as a favourite!)
I did a search for a Saturday, looks like you need to get the
Number 7 Stagecoach service from Chorley rail station, getting off at Charnock Richard Park Hall Entrance, followed by a walk along the road to the park. Takes about 30 mins all in all.
I would use that site for the day you're going, as the bus services may differ.