According to my girl, they now have SCA which is from 3:30-4:30pm and CCA which is from 4:30-5:30pm. For CCA you have to make your own arrangement cuz school ends at 4:30pm.
In the official website, it says "The Education Bureau stipulates 50% of places can be given to local pupils with Hong Kong passports and 50% of all pupils in the Upper School (from Year 6 and above) must be weekly boarders." May I know if you son is boarder?