Mine were all older than that when they went, IIRC they were 8, 11 and 13. I don't think there are many kids under 7 there right now. I'm surprised by that Neill quote tbh, I'd have thought that the worst part of schooling occurs when you're older.
As for going for just a year or two - not sure I can give advice on that. Zoe Readhead, the principal, is very approachable - she could help you there.
If you've any questions you want to ask me offline, I'm at <hn user name>@gmail.com.