Original!
I am also a loyal follower of the Imperial Cult and a die-hard guard-collector! (I am not saying anything like Guard rules and Tay suck...that is just soooo pathetic) I liked this movie and I hope to see more of this. The only thing that was missing in this movie is the excessive gore common when fighting the 'Nids.
+++ As for your battle: Make it brutal, messy and unlike any warmovie or book around. Show the people the true face of Warhammer 40.000! Have people backstab each other, men getting shredded by aliens, bodyparts littering the field and a heroic last stand by an army as they rally around their banner for the valiant (but hopeless) last stand. Quite dramatic, but neat!
One last question: Which armies do you play? (A question from one wargamer to another.)