The fowler offered by TVM is a functional and a decent handling gun. However, I am not a fan of straight barrels. The handling of a fowler with the tapered and swamped barrel is much superior.
Let us know a little bit about your level of experience with wood and metal work. A kit can require quite a bit of wood shaping and inletting work to get the parts to fit. You will likely need to drill and tap the lock bolts and tang bolt. You will need to dovetail the sights and either dovetail the mounting lugs or drill and rivet the lugs. You will also have to drill for the stock pins to attack the barrel to the stock.
Do you have any of the muzzle loader building books such as "The Gunsmith of Grenville County" or "The Art of Building a Pennsylvania Longrifle"? What tools do you have available? You need hand tools such as small chisels for inletting, three cornered files with one safe side for dovetailing, files and smoothing stones for polishing of the metal parts.
I would do my searching for a fowler with a swamped barrel. Jim Chambers Flintlocks offers several fowlers with tapered barrels, an in-the-white option that I recommend for first time builders. Other sources are Tip Curtis, Mike Brooks and many others. These may be more expensive than the TVM kit, but the performance is decidedly improved.