I don't think so, as education continues to be government funded until you are 18, and he will still officially be in full time education until then. His work will be in addition to his full time education. Just be sure that he takes out appropriate insurance, and doesn't attempt to do any work that he is not trained and certified to do. He should look to get some work experience with a reputable company where he can build his experience and still work on a self employed basis.