Go to the NMLRA web site and look for Eric Bye's book, "Flintlocks, Their Use and Application ". It's well worth the $33.
As far as flintlock tools, you need the basic tools for any traditional muzzleloader.
Working rod of brass or stainless steel with muzzle guard and jag of appropriate size for the barrel.
Ball puller and patch puller.
Volumetric powder measure 10 to 120 grains powder.
Powder flask to dispense powder.
Lead balls of a caliber for your rifle.
Cotton patching for round ball of approximately 0.015 to 0.018.
Patch lubricant (from spit to exotic oils and greases.
Short starter
Patch knife if patches are to be cut at the muzzle.
Specifically for flintlocks:
Black Powder probably 3Fg. Don't waste time trying to get the synthetic powders to work. The 3Fg powder will be acceptable as pan powder. Uses the measure to pour the pan half full. No need for a special pan primer just yet.
Tooth picks or bamboo skewers to plug the touch hole for cleaning. A rare-earth disc magnet with an electrical tape gasket will work also.
A touch hole pick to keep the touch hole open.
Rags to keep the pan clean.
Larry Callahan's flinters tool. It has properly hardened and sized blades to turn screws and bolts. A vent pick and knapping notch.
A hammer stall, a leather cover for the frizzen to stop the flint from striking the frizzen.
Black or amber flints sized for your lock.
Optional flash guard to attach to the pan to help control the pan flash from being directed to an adjacent shooter.
Find an experienced flint lock shooter to mentor you through the learning process.
There's lots more tools, but these should get you started.
@matt48, welcome to the experience of flint lock rifle shooting.
Being in East Anglia, Germany, finding real black powder may be your biggest challenge as well as some of the tools.
