The Priory Group have some excellent guides.
Guide on childhood anxiety
Guide on teenage depression
A comprehensive list of eating disorder helplines

Here are some links to organisations that can support young people or those working with them:

Life Coach – Youth Coaching – Some information on coaching for young people and the benefits it can have.

MyTutor have a page outlining mental health issues young people might face in education and a series of helpful links.

Counselling Directory – A confidential service that encourages those in distress to seek help. The directory contains information on many different types of distress, as well as articles, news, and events.