Downloading instructional video's and practicing with friends is a way to improve your BJJ, if you don't have access to BJJ classes. There are a few fighters in the UFC he learned BJJ this way in the beginning.
Also there are many exercises you can do on your own which will improve your BJJ as well. Perhaps searching for BJJ workouts or something similar.
The link below may help:http://www.grapplearts.com/Bodyweight-C ... cises.html