I gave up on the "PPL theory" idea after some more thinking. This gap between the theory and the practical part could result in some problems down the line. Besides, it still isn't equal to a full PPL (lack of practice) yet you give the interviewer(s) the chance to have a dig at your PPL knowledge.
It's better to have some knowledge when asked than no knowledge at all. If you want to be a professional pilot, now is the time to act like it. This is a profession of continual learning and adjusting, and if you're squeamish about being wrong, this is not the industry for you.
You are correct that there is theory in aviation that requires practical exercises and without said practice, you could be in trouble. But this does not really apply to the PPL as much as an Instrument Rating. Knowledge regarding meteorology or navigation, principles of flight or general aircraft knowledge does not require in-aircraft training. A solid understanding of the basics through pre-reading will often make you a better student in these subjects when it comes time to have you apply the "one-in-sixty rule" or "double-track error method". A cumulus cloud is a cumulus cloud because of the stability of the air. It does not require you to be in an airplane to know that, but it does require that you read a book or two. Your PPL theory training is not the place to find out that you don't have a solid grasp on trigonometry or physics. Better to find that out now and be able to fix it than fail your course.
Getting questions wrong is not a harbinger of failure in anything but an exam. Sometimes it's quite the opposite. When I conducted interviews for a previous airline, I would look to see how someone reacted when they were called out on their incorrect information. If they accepted their error and showed a willingness to learn from it, then that was fine - I could teach that person. Being wrong is OK (outside a written exam). It's how you handle being wrong that is of most concern. As I said, this is an industry of life long learning, and if you're worried today about people "digging at your knowledge" then you are in for a very rude awakening when you get to the airlines because that's all we do.