I would find a class that prepares you for the CGC.. But I do know if a dog shows agression and shyness/fear they will fail.
I just did the CGC with my young dog.. And for the most part it's you and the instructor during the testing... Other than when they bring in another dog handler team for you to approach and greet and then the group of a few people milling around for you to walk through..
Have you looked at the test to see what's all involved??
Chaos v. Wildhaus, SchH2, OB3 (HOT) ~ Bismark v. Wildhaus, SchH1 (HOT) ~ Kougar v. Wolfstraum, Bh, CGC (HOT)... And now Oberon v. Wildhaus ~ the obnoxious puppy..