Hey, just to say you posting this reminded me to finally get around to reading the full IC thread. I'm sorry it took me so long! It is great, I love how rich the character development is and I will keep up with it in future. The central premise is a really interesting, the narrator is relatable and these are all people I'm happy to spend time with as a reader. I don't see myself forgetting the story so far any time soon.
Also - not that it matters, as Ben rightly pointed out before - I couldn't see any canon conflicts with new GW material, or none I'm aware of. Given how far into the future you are, I think you'd have to include something pretty extreme from between M41.999 and M42.111 to run any risk of that being a problem. I didn't find anything from GW dated later than M42.111, hence setting our story in M42.120 to place ourselves slightly in the future. The Great Rift opened at the turn of the millennium, Guilliman came back to rule as Regent in early M42, then spent the next century leading the Indomitus Crusade to retake parts of the Imperium - those seem to be the fundamentals of the new stuff, if you leave aside the Eldar death cult, but anything could have happened since then and you're deep in M44. Given how much the 40K universe seemed to change between, say, M41.990 and M42.090, piling two thousand years onto the timeline pretty much allows you to do away with anything you like in the course of history. E.G. Plenty of people were trying to close the Rift, maybe someone succeeded. If that happened within even a couple of hundred years, maybe the whole thing isn't thought of as a big deal from the perspective of people in M44. The way I see it, there are infinite possible futures until you get there, so from a present-day 40K perspective you aren't necessarily creating destiny, merely exploring possibilities. We're actually in more danger with M42.120, in case GW subsequently decides Belisarius Cawl closed the Rift in 115 or something and it turns out we wrote the bugger in for nothing...
(I know the Imperium technically writes dates with the millenniun at the other end but I've hard to start doing it this way round for the sake of my sanity!)
Keep up the good work, anyway. Just wanted to reassure you your work isn't going unread!