I would highly recommend flying to Jimmy Lewis riding school and just rent one of his bikes. IMHO, you are not going to get any better than his school for off road skills.
You do have to have some basic clutch and braking skills. You will use a lightweight bike for the class. He does not recommend bringing a large ADV bike. The skills required to ride the large bikes are exactly the same as the small ones. Only difference is the mistakes and weight of the big bike are amplified and will wear you out. Trust me you are going to learn a lot in his class.
Sign up for the news letter and you will get first chance at getting in. It is next to impossible to get in without signing up. After you get dates for the class they fill up in just a few days.
Here is a breakdown of minimum riding skills required and what category you fall into:
And no matter what anyones opinion might be, no open block knobby no ride. Jimmy is a stickler about having open block knobby's in the class. If you ride in with an E07 you will be doing a lot of dirt naps.