I'm not sure that the CAA would care. There is no requirement to follow an approved course for the PPL written exams, you just do whatever you need to do to pass. So no need for CAA approval.
(If it was ATPL or CPL exams, it would be different - you need to follow an approved course for these, so the course would need to be approved unless it was intended to supplement an approved course.)
FFF
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