Would Be Gunsmith
You have one of the worlds best resources right here at your finger tips.
Read and search this site and you will find everything you need to get started.
I am in the same position as yourself, I have been reading this site for about 2 years, I print off threads that contain pictures / descriptions of the tools these guys use (then build them), keep descriptions of the processes & proceedures they recommend.
I send emails to the regulars on this site asking questions, (I do not ring them as most are busy, they will reply when they have the time!)
Practice the operations required, facing, cutting to correct size, threading etc. Trying different techniques.
Steve Acker's book "gunsmith machinist" is a great buy off ebay!
I will be building my first rifle this year! yes it has taken 2 years to get it all together but this site and the people on it have given me the best schooling / tutoring I could possibly ask for, as we have very few gunsmiths let alone a smithing school over here!!
I wish you all the very best and welcome to the fascinating world of rifle building