Depends a lot on the student and teacher. I think it is only truly worthwhile to have regular English tutoring (at a Year 12 level) if the tutor has studied the book his or herself. With the obvious exception of language analysis, it allows the tutor to help with your writing style, but also give really worthwhile readings into the text/context which they know actually work in an essay.
When I tutor English, I read over their essays, often comparing my own thoughts with comments suggested by their teacher if applicable. I also show them some of my essays, give out guidelines and tips to constructing the different types of essays (including "hot" phrases or language techniques to look out for), go over vital scenes and quotes from each text and the ideas covered, as well as example paragraphs of how those themes can be used, relevant real world examples and philosophical quotes for an expository essay and also practice at the hardest part of essay writing - the planning stage for obscure topics. Usually this is covered in a rather hefty set of notes written when I did Yr 12 (which is the reason why a teacher who did your texts is so important).
Hope this helps