I am contributing my suggestion for a revision of your thesis statement. As answer 1 suggests, I don't believe he actually criticized the lack of education in France. He probably couldn't have criticized public education because it probably didn't exist. You should avoid repeating the author's name, as etotheeyepi and I have both indicated. I am not entirely satisfied with my version of the thesis statement. Maybe what it needs is some suggestion of how he thinks social reforms could be achieved. I think you have a good idea for approaching such a gigantic novel.
In his novel Les Miserables, Victor Hugo advocates social reforms both directly and implicitly by dramatizing and describing the conditions that are in the need of such reforms.
You might say:
In Les Miserables, Victor Hugo advocates reform of the French justice system, and he criticizes the lack of education in France.
I don't remember that Les Miserables says anything about education. I must have skipped that page.