You may be able to start as a school administrator or secretary. You'll usually need 5 GCSEs, including English and maths. With experience, you could apply for promotion to office manager or business manager.
If you're already working as a school administrator you could take a qualification like the:
- ILM Level 4 Diploma in School Business Management
- ILM Level 5 Diploma in School Business Leadership
Visit the Institute of School Business Leadership for more details about training and qualifications.