*looks at the pic*
Rather than playing that guy, would you want it as a minion? I could see that being something like a weapons servitor for a Nurgle aligned Heretek from the Dark Mechanicus .. someone who has fun crafting flesh, technology and deamonic essence into something new.
Black Crusade allows the PCs (according to the stuff on the FFG site) to purchase and customise minions that can help cover the area's that they're weak in.
A knowledge of 40k, and in particular the forces of Chaos would definitely help in playing.
I can recommend a few novels
The Night Lords ones by Aaron Dembski-Bowden, Soul Hunter and Blood Reaver. They feature the Night Lords.
The Word Bearers novels by Anthony Reynolds, Dark Apostle, Dark Disciple and Dark Creed. These are about the Word Bearers.
The Soul Drinkers ones by Ben Counter, Soul Drinker, The Bleeding Chalice and Crimson Tears, which shows how a loyal chapter can fall (though it does need a bit of suspension of disbelief at times)
Blood Gorgons by Henry Zou, about a renegade chapter.
Most of the stuff in these focuses around various Chaos Space Marines.
The more human followers haven't gotten any real major lines of their own, but there is some stuff in the Gaunts Ghosts novels, and the various Inquisition ones.
It might even be possible to cobble together rules for Orks or Dark Eldar, as both of those would work with Chaos. Maybe even the Kroot mercenaries, lifting those from Rogue Trader.