Having used an Aquaris E4.5 (the original Ubuntu edition) for over 8 years I finally decided it was time for a upgrade and ordered a secondhand Pixel 3a. The E4.5 is still working, just a bit slow.
Thanks to the threads on here, I got through all the steps in less than 15 minutes with absolutely no problems 
Using the Chrome / Android Flash Tool method suggested by @MrT10001 then the UT installer, it all went fine.