In Loudoun I would get in touch with Bryan Mossey who teaches at One Spirit which is where Pedro Sauer teaches BJJ as well. Great guy and an excellent FMA man. He also teaches their Muay Thai classes. Other than that, the closest I know of would be Trident Academy in Woodbridge. If you are in east Loudoun (e.g.) closer to the metro, there are some other options but I would start with Bryan Mossey.
Saw your post about FMA in the Northern VA area. I live in Loudoun County and was looking for a school that was relatively close by. Any suggestions?