Hello Rob
3B+ is actually better than the earlier versions of Pi and there is an image that works. There is a link on this forum somewhere, rachel_pi_kolibri_10_30_18 provided by James.
There appears to be an issue with Kolibri provided by worldpossible but it is possible to install Kolibri directly.
I have tried to put together some notes from what I had to do to get things to work. You are welcome to have them they are at Technical - Giakonda Solar Schools
Kind Regards
Howard