My first kit was a TOW English Fowler and I was in much the same position as the OP. I paid them to fit the breech plug and underlugs. The whole enterprise was rife with issues. The underlugs were all off center in different ways from each other, and I later found out the plug was installed incorrectly. The barrel required a trip back to them and then yet another trip to an experienced builder who graciously helped me out and fit the plug properly. In retrospect, I know now that the wood they sold me is pretty much garbage. It's rife with soft spots and made my first efforts at inletting all the more difficult. Knowing what I know now, I should've sent the whole steaming pile of turd back to them as soon as it arrived.
For your first effort, you should get a kit/component set which allows you to build and learn in the easiest manner possible. The style or school of the gun is certainly of secondary importance. You want to be able to learn and accomplish things with as little unneeded frustration as possible. If you like muzzleloaders, other guns will follow. For your first, choose one which allows you to best succeed and learn. You should also go somewhere where you can handle a bunch of guns and talk to the guys who do this alot. The traditional muzzleloader community is very helpful and friendly to beginners who can take constructive criticism and want to learn. You should definitely go to the Dixon's builders fair in PA before you do anything else. That would be a great place to get some hands-on perspective and learn a bunch.
TOW has a great selection of parts and accoutrements, and they ship things fast, but I'd look elsewhere for a first-timer's kit. A Kibler gun would be the easiest/fastest to assemble, but much learning would still happen. Chambers or Dunlap woodcrafts would be more involved, but you'd still have a quality foundation to build from.
