Thank you JonB for suggesting Dropbox, ccc for suggesting how to get the path from file and thank you omz for describing how to run python 2 in pythonista 3.
My script now works on iPad, a transition which I thought would be much harder to achieve than it was.
Pythonista was recommended to me by someone who actually works in IT, not a recreational programmer like myself. In my short time using it I must say that I'm impressed by how easy it is to use. I love how the script editor works. And this forum is the business!