You have three weeks to find/buy a bluecoat soldier, otherwise I'd recommend you to use a decal.
It just has to feature one bluecoat, but of course you could lay the focus on an enemy avatar of which you do have the torso.
You don't have to think of a story surrounding your minifig, but we will probably get to know him through the comics.
Finally, I can recommend you to choose the Bluecoat side.
We drink just as much as the redcoats, but the difference is that we do get our senses back in the morning and kick them drunkard's @sses, you'll see!