There's also a lot to be said for having an interest, or better still, a passion for aviation. If you're going to spend the next 40 years doing a job, it's far easier if it is something you enjoy.
Your PPL and ATPL level of knowledge are worth a lot more than being able to identify what shape box a flat piece of paper will make! A reasonable level of intelligence, a big chunk of common sense and the ability to be flexible are better attributes than academic qualifications.
NATS have never quite got the selection process right, which is why their failure rate is still so dismal.