For free resources, including worksheets, test and discussion guides to use while teaching "James and the Giant Peach," visit TeachersPayTeachers.com and RoaldDahlFans.com. Roald Dahl's webpage at RoaldDahl.com also provides a lesson plan.
Teacher'sPayTeacher's has several free packets of worksheets available, but it also has several more comprehensive collections available for purchase. Many of these worksheets focus on character analysis and vocabulary comprehension.
RoaldDahlFans has compiled a list of other resources for teaching "James and the Giant Peach." This list contains tests, vocabulary work and comprehension questions.
Roald Dahl's webpage provides a lesson plan that includes discussion and activity ideas centered around James' terrible aunts. These activities work for groups or individuals.