http://www.clubarnage.com/caguide/
This is as good a guide as any. I know its 2013's version, but the campsite and access info is (and hopefully will still be in 2015) relevant.
Its written by fans with many years experience of the event down the years.
By way of planning for 2015, maybe you should visit in 2014, watch the race and then your planning for 2015 will be a lot easier.
