Bufit,
If you have the opportunity to shoot at the Nationals, go for it!
It's up to you if you "have a good time and learn", I always do
It doesn't matter if you are a "nube C class..." as BryanW said there are lots of C class shooters. There are also D class shooters and unclassified shooters. There are guys I shoot with who tell me they won't go to a major match because, "I didn't do well at my last match" or "I want to get better before I go to a major match"...
Shooting is way more fun than watching
Sign up and hope to get the chance to shoot.
barry