At http://2016.pyconuk.org/ we just ran a fantastic kids day - about 60 children with parents using pi-top ceeds, to program minecraft and then connect their microbits (one each free, thank you sponsors) to raspberryPIs gpio and so on. This was arranged by RPi foundation and used micro Python and was a great success
As one of organisers of PyConUk obviously I say use micropython , but whichever you go for I hope it is as great as we just saw
Just be ready for a lot of work
If you want contacts please ping me - paul@mikadosoftware.com