No, the young homeless woman with the thuggish boyfriend/possible pimp is not in any of the books. Dave and Julie don’t appear (as the film only deals with the first part of the walk, not the second leg where they meet them) either.
I have no issue with changes/ new scenes for a film adaptation, though. Things that work in a memoir often just don’t translate to screen at all. I think I said several threads ago, under a different username, that I was on a tv series set last year with a friend whose novel provided the basis for the screenplay, and it was very interesting to see what had to be changed from a novel with several first-person narrators and not much action into something that works onscreen, where someone has to be performing an action or speaking. In a screenplay, you have to be able to show everything. Or use a voiceover. I imagine one of the issues with turning TSP into a screenplay is that it is mostly just two people walking and camping. No real other characters, very little dialogue, lots of people who only appear for a single scene.
So the screen writer condenses all the scenes where people apparently recoil at the Walkers’ homelessness into one (the family at the tearoom) and makes Tim’s withdrawal from his drug much more dramatic, and condenses the various ‘visited by a heavily symbolic animal’ scenes into the peregrine etc.
I assume that getting the crew and equipment to many parts of the path was impossible, so they had to film where they could get to, explaining the oddities of location in some places.
I totally agree with rabbits were ridiculous, though. It was like an episode of Teletubbies.