Black Jaque,
Welcome to a great adventure.
You have made your choice in selecting a rifle. It matters not from whom or what style it is. That decision has been made. It's now your job to put it all together and do the absolute best you can do.
Firstly there is research. Buy the books or at least a book. The Grenville book is good as a matter of fact it's great. The thing about Alexander's book is that it's wordy (written in Canadian) and it takes several re-reads to get the point. I hear Dixons booklet is very good and very brief and then there's the Shumways Recreating the Longrifle that many like as well or better than Grenville.....
There's also several DVDs and videos. The forums are a good source especially when people share their mistakes and ask for and receive criticism.
Study the longrifle. On here is the best online source period. Visit the museum here. Look at the originals. If you can, go to shows an view and maybe handle originals and good contemporary rifles. Take note in how the light reflects the surface. By this study you develop your minds eye and hopefully you'll be able to project that into your hand work.
There are things that have no answer...no instructions. Lets take forming a lock panel. All you get is a general description. Not a Do this just like this and you will get ...this. The reason that some things are vague, is there's not enough words to explain it. You get the basics, the rest you will have to figure out. Once you do it right you will know. I'll tell you this, having the right tools helps tremendously. It's possible to build a longrifle especially a pre-carve with a pocket knife, file, cold chisel and a brace and bit. Would it be easy? Nope!
Here's my tool list.
1/8 or so bench chisel....small enough for cutting curves
1/4 bench chisel.
a gouge for like the lock inlet nose
sharpening stones
leather for a strop
strop rouge
hacksaw
a good file
a combo square with awl
a safe sided triangle file
a light hammer
a heavy hammer
a drill
a cold chisel
a # 50 pattern makers rasp
Sand paper and or scrapers
work bench with a vise.
set of gunsmith drivers... hollow ground screw bits
good lighting
tape
pencil
glasses or opti visor You can't work on what you cant see
large crescent/Monkey wrench....I use an ancient slack jawed "steam wrench" for breech plugs
That's pretty much it. A drill press or special jig/dill guide is helpful for drilling pins and bolts.
Oh I almost for got a bottle of good wood glue, you'll need it.
Do the best you can....why do otherwise?
I am fortunate enough to be able to study under a master. He's got my back if I run into to trouble. Maybe there is someone close to you that you can study/work with. If not there are classes available.
Many masters are on here. If you run into trouble ask for help on here.....
Good luck and have fun. Every time I approach the bench I have a grin. I may not leave it that way but when I start every work session I'm ready for work and problem solving.