Teaching with Moodle

Our institute offers students the option to access course material for a six month period for self-study auditing. Course resources include audio, video, and docs in various formats. We use WordPress for this functionality. Access is controlled by means of group permissions--a student is made a member of the course group for six months, after which time their group access is revoked. The system works well and WordPress is set up to authenticate against our Moodle database, but it's far from perfect and I would prefer to deliver this functionality through the Moodle installation we already use. Can anybody outline a way to do this in Moodle 2.x, either through the default setup or using plugins? I have been looking around but I've hit a wall. Thanks.