Update: I spent $500 for a 5 year old 1 tB hard drive tower with windows 10 pro on it.
I spent $150 for a piece of shit tower for my offline computer. Literally the cheapest tower in the shop. Windows 10 pro running on it.
Got it all working without any headaches.
I battled with Ubuntu on a laptop and an external drive for hours upon hours and never got it working.
Hope this helps others.
Suggestion: a pinned comment should reccommend Windows and not Ubuntu for non-techies.