I have found a great resource for starting your own chess club at this link: http://www.rockfordchess.org/clubs/starting.htm
I loved the table where they discussed “Optimal” vs. “realistic” playing conditions. The school I work at certainly falls under the latter column. Granted, starting a chess club in an after-school program will be challenging but if you persevere it is likely to be a very rewarding and fun experience for the children (bonus: parents will appreciate it too!)