Can't be done. How are you meant to produce age appropriate resources for that will cover everyone from age 11 to 16, especially in key areas like sex and drugs. This is know more than lip service to PSHEE. Encourage the decision makers to timetable PSHEE as a lesson and have it taught by volunteer teachers. If I was in your position i'd use the time for an active Citizenship project lead by the yr11 students but involving the rest. "Giving Nation Challenge" could adapted for this purpose.