I seem to have fixed the issue after 2 days on it.
I downloaded and installed Adobe Application manager.
I copied Photoshop and InDesign onto my laptop from my iMac via memory stick.
I launched photoshop and just clicked for a free trial.
Then I launched InDesign, which crashed a few times.
Restarted and launched photoshop again.
Clicked for free trial.
Launched Creative Cloud.
Finally not a blank screen.
Restarted again.
Launched Creative Cloud again.
Finally got a sign in screen!
I think the trick was to install Adobe Application Manager and then just keep on perservering trying to launch photoshop and indesign until it stuck.