Confidentiality is about keeping your information private. Feeling comfortable and being able to talk freely in your appointment with your mental health professional is important.
When you first come to CAMHS your worker will mention confidentiality. All the workers in CAMHS write notes about what has been talked about during your appointments. Sometimes they will write to your GP or other people with your consent.
The NHS has rules about keeping your information private. Your information is stored in your health notes on a computer system.
You might want your worker to share information with your school or with other professionals in your life. Your CAMHS worker would discuss that with you before sharing anything.