I took previous advice in this forum and finally gave up on the ugrade route and did a clean install. i took the pain (despite backups) of reinstalling everything and yes, agree that it would have saved time and effort if I'd done this first off.
Which leads me to wonder, depite the tutorials and advice given here, whether anyone has managed a first time, no glitches, smooth and easy upgrade? It looks like the easy option (especially for a naive user) but it is not - at least in my reasonable years of experience dealing with operating systems.
And yes, I should have known better.