After a few hours of messing around with this game I was able to find out how to skip the Sawmill and the Lion Maze.

There are plenty of other sections you can use this glitch on and leave the area, like the Post Office to fall out of bounds and land on the table where the three letters spawn, however the Post Master will not spawn so you cant continue the chapter. You can clip into the attic in the haunted house to skip all of Erins ghost conversations etc but the 2 books wont spawn. It seems there are loading triggers for next sections everywhere but I never messed around enough to find them to make most clips not viable.