I've contacted Immigration twice now and they've simply sent me straight back to the website - so yes, about as useful as a chocolate teapot!
Many of the Visa's exclude public education, or are for only longer than 6 months or are really for older students attending a specific course.
https://www.gov.uk/child-study-visa - excludes young kids and public schools. paying schools fine (but it's for a specific 'course')
https://www.gov.uk/study-visit-visa - excludes normal education - short courses only
https://www.gov.uk/child-visit-visa - this one I'm not sure about - says no public education unless part of exchange or educational visit
https://www.gov.uk/family-visit-visa - this one says he can't study for more than 30 days.
https://www.gov.uk/join-family-in-uk - this one is as if we're there and he's coming to stay permanently, which he's not.
I just find it hard to believe that people don't get contracts etc in the UK for x months and have their family with them? What do these kids do in the meantime?