You are right; they are wrong!
The CAA questions are not exactly the same as The Confuser although there are similar ones. In addition, The Confuser does have a couple of error so be careful.
Reading the books will give you a good understanding of what you need as a pilot; at the PPL level, this is the useful and necessary stuff so you will be a better pilot for having covered it rather than just practicing questions.
If you think you might be going onto the professional exams, then a good understanding at this level is almost necessary, otherwise you could find ATPL difficult.
Good Luck!
Cheers
Whirls