Solved the Mapping Problem

Following on from my previous blog I'm now thrilled to say that I've solved the problem! For the benefit of those who care, here's what I did.
I checked I had Google Earth installed.
[Update: latest blog for list of Railways near Canals]
Choose the downloaded kmz file to open in Google Earth.
Knowing I wanted mainly railway lines and stations I selected More > Transportation > Rail in the Layers panel and unticked mostly everything else.

River Ouse and Railway Bridge at Ely

Finally in the Places panel I ticked My Places > Temporary Places > UK_Canals_Route_only and ticked absolutely everything within that. If you're only interested in a small number of canals you need only tick those you need. Screenshot below with Ely station highlighted for clarity. The Ouse is lined in blue.

So here's my next (or the one after that...) project - noting railway lines near to canals so I can moor up, catch a train and come back later - or friends and family can catch up with me while I'm away.
Next, to find friendly folks who will accept me mooring for a short while and where I won't block anyone else - a bigger problem altogether!