Most popular skis today are about 78mm and up. Skis are getting fatter every year. For 200lbs, in Cascade glop, I'd say 75 and up, at 180-190cm long is fine. As the waist of the ski gets fatter, the shorter the ski should be. And remember: it's much easier to learn on shorter skis.
As for instructors, I never had the money, but I had a few friends who helped me out. If you do have the money, a lesson or two will probably help shorten the learning curve.