can I tell google maps to avoid motorways?
The following seems to be the answer though I haven't put it in practise yet.

in google maps, choose navigation, then in the bottom right there are 3 horizontal bars, then  it has options of "routes and alternatives, directions list, layers, turn off voice, exit navigation, more".  Choose "routes and alternatives" 

Then it has 4 buttons..

A button with a blue arrow,  

A button with 2 cogs

A button with arrows pointing to what looks like a raindrop.

A button with 3 dots with 3 horizontal bars alongside the dots.

Click the button with 2 cogs.

Then it says Route options.  Avoid motorways.   Avoid toll roads.  You can choose "Avoid Motorways".

I'll include some pics when I can.