Are you both aware of IGGY? My DS has not yet done any of their courses - dates have yet to work out - and there seem to be only a couple scheduled (I hope this doesn't mean they're winding down) but we've looked with interest, as it might be a way to get a bit of extra challenge and a chance to meet others a bit like them. (I understand they can be flexible with ages, btw.)

Email: my username, followed by 2, at google's mail