It looks like a pretty normal trench coat. My friend & I were all over the mall the other day since I was looking for a cosplay jacket as well, and we found plenty of them. It's the perfect time to go to any store like Sears, Macys, etc. because jackets/coats are on sale (I bought mine 60% off). I believe the material could easily be bleached, so even if you don't find the right design/color match, you can just bleach/dye it. Or you could alternatively buy a white trench coat and sew on pockets from old cargo pants, buttons, and straps. While you say you're not good at doing that kind of stuff, these are more minor sewing things and should be simple enough.
I hope that helped.