Soo I'm getting this whenever I try and start a campaign or the skirmish. It's baiscally exactly the same in-game error you'd get running the original disk version of the game if you started it up, but didn't put a game disk in. So something has t obe going wrong somewhere.

For reference I'm running win10 and an RTX 2060, I do also have a disk drive in the computer (incase that might be an issue?)

Me too, i did done simple in "Manage installation>Verify / Repair" and it's fixed.