The Clicsargent web site provides excellent information to support parents and children, as well as for siblings.
Factsheets and leaflets can be ordered free of charge.
Macmillan Cancer Support has a a section on-line for young people affected by cancer, they also offer free publications. Advice includes help about when to tell children you or someone close has cancer, and how to explain treatments.
There are also sections on the Macmillan Cancer Support web site that offer help to teachers in schools.
Cancerbackup offers help and support in many publications.