Thanks for that Theo.
When I came back earlier I tried Noobs on a range of the uSD cards I had to hand and eventually one seemed to work, downloaded and installed Raspbian.
WiFi worked OOTB and the whole thing feels very much more useable (as a GUI workstation) from the short tests I've done so far.
I just left it running an update.
I haven't looked at the specs of the cards I have but am waiting for a few 16G Class 10's as they were only a few pence more than class 4's (FWIMBW).
I may try a fresh OctoPrint image on the RPi3B later but if I can get the hang of running it from the CLI then I should be able to use the RPi1B I bought earlier.
Cheers, T i m