Well an update report, a guy with the same issue (but in his case trying to upgrade to win10 from win7), said he googled someone removing hidden volume devices to fix it, so I tried that, I had over 15 hidden generc volume's in device manager, it didnt fix it but the fail point moved to 58%, interesting. I then removed some hidden sound devices in device manager which said it couldnt detect them on the system, the fail point is now at 55% copying files.
Lots of issues here.
1 - the install process for devices is broken on win10, has happened to too many people. It worked on win7/8 so not sure what microsoft have changed to break it, possibly that win7 would ignore issues and proceed with install and you would then have to fix manually after install.
2 - the upgrade process to a new win10 build repeats the entire process, why? the OS is already installed, this has a lot of issues, such as the one I am having, but also if someone has spent the time manually fixing drivers, I assume those changes would be undone with the update that refreshes all devices drivers.
3 - why is the installer lying about copying files when its really setting up devices?
So given I have moved the fail point I am guessing this is some kind of device driver issue.