I think a lot of historical novelists do a lot of research and pride themselves on their accuracy, for example, Hilary Mantel (Wolf Hall). But she has to fill in a lot of stuff, for example, conversations and meetings, where there is no record. The TV version did get criticized to a degree, e.g. Thomas More was shown as something of a villain, whereas everyone remembers Paul Scofield's beatific version in 'A Man for all Seasons'.
But the Tudors do attract a lot of writers, and for some reason, people get very upset about some portrayals, how dare you show Anne Boleyn as a scheming Protestant bitch, she was a nice girl, and Henry was a knob.