THERE IS A HELLSING MANGA, READ IT PLZ!!!
This has been a public service announcment by the Society for the Promotion of the Hellsing Manga. You can check out all things Hellsing at BloodKnight
. Which is run by RipVanWinkle
But really, if you want to check out the manga scans, it's got alot better shots (I think) of the costume. Also, there's three different variants of the color scheme, so make sure you pick the one you want. For patterns, I couldn't tell you where to start, but whatever it is, the collar will have to be done custom...nothin like that in any Simplicity catalogue or whatever. I'd check for something maybe along the lines of uniforms?
Again, whatever you do is going to require customization, it's just up to you how detailed you want to get with it.