You could gain a job as a construction site labourer and gain experience using heavy plant machinery before training as a crane operator.
Alternatively, you could apply directly to an employer for a job as a crane operator and learn under the supervision of an experienced crane driver.
Work experience
Work experience is essential to gaining employment within the construction industry. You could gain this at school, or by working weekends and holidays with a company or relative who works as a crane operator. Potential employers will always be pleased to see work experience listed on your CV.