I've now realised that if you follow the upgrade process for Moodle on the Bitnami page, it also upgrades the stack - I think this could be a lot clearer in the documentation for upgrading Moodle versions, as Moodle makes it clear you need higher versions of php too, and if you ship that, that's great, but you could make that a lot clearer in the documentation, like right upfront.
Now I have upgraded (now I've got the right version of moodle and php7 too) but now I go back to my moodle site and all I get is the Apache2 default page - see dojo.code4000.org . How come? There is nothing on your forums or docs about what to do in this instance. How do I get my site active again running the new version of moodle? This is urgent.