I was once very into historical fiction and so I really wanted to watch this show but I was about 13 at the time and found out that the Tudors was rated TV-MA, nevertheless I watched it and yeah it has a lot of sex but if you know what it is and if you're mature enough then go ahead because the story line is good and it has a lot of politics.
I am personally 13, and the sex and violence is pretty graphic however I guess if you're mature and such it doesn't matter. I love the show because of the history, characters and interesting story line. Besides, the language and such just adds depth to what is happening.