What rooms are likely to have been on an Astates ship specificly would there have been something similar to a chapel?
I need it for my fiction entry.

I wouldnt think that anyone but the Word Bearers would have, because i dont beleive that they had chaplains before Nikaea (did i spell that right?)

Similar in appearance or similar in function?

Similar in appearence, mainly as i don't want to write about the WB.

The entire inside of the ship would look like a gothic cathedral. That's the Imperial style.