For those interested I've posted up a BatRep of my first foray into "Warhammer 40K" using the free downloadable rules... and a couple of tweaks. Only 90 points per side so we could just get our heads around the basics without too many unit specific rules.
Hopefully this'll be the start of a bigger campaign, as extra models are painted and added to the two opposing forces.
https://fantorical.blogspot.com/2019/04/warhammer-40k-report-black-templars.html