In the best of worlds, you and your husband would have different shifts so that one of you would be around to set up study times, check with the school, and give him the attention and boundaries that you are unable to provide at this moment. I urge you to check into that possibility. If your son continues to go unmonitored, he could quickly become involved in drugs, cutting classes, vandalism, etc.
My only other suggestion is to look into getting him a big brother or a mentor from the community. You might check with the school about whether your community offers such programs. What about after-school programs for teens? I strongly recommend that you and/or your husband take a day off and check into all the possibilities -- both for your sakes and his.