I often recommend this career path to people and advise looking out for when NATS are recruiting.
They have just opened their recruitment window for ATC trainees:
Trainee Air Traffic Controllers - NATS
Not many people can do this type of job so the rewards are high if you succeed at selection and training. Anyone 18+ can apply with GCSEs (no A-levels, degree, or experience required) provided they have the right to work in the UK and meet the medical requirements.
Even if this kind of career never appealed to you before, it's worth having a look at the page linked above and trying out the online tests.