Like others have said, the 5F1 circuit is pretty simple. If you're going to go the kit route, I'd look at
www.triodeelectronics.com. They have a reputation for being slow to ship, but their kits come with Classic Tone transformers, which is a brand I've become a fan of.
If you just want to gather parts and wing it, get on Google and search for "guitar amp schematics", "guitar amp layout" and "guitar amp BOM" (BOM being the acronym for Bill of Materials). Then you can get creative and use damn near anything metal for a chassis. Heck, some peoe use cake pans, ammo boxes, or whatever for simple builds. Then Google up Classic Tone, Heyboer, and Mercury Magnetics for your iron (transformers/choke). They are the three main brands that builders go for, and they all have good reputations for making good sounding and durable stuff. Classic Tone and Mercury both have well laid out sites that will guide you to what you need. Heyboer is more of a custom, one at a time kind of shop, so you will have to call them to talk about what you need, but they do make a good product.
As far as tubes go, I've ordered from The Tube Store and Doug's Tubes. Both are good outfits and have slightly different selections. And the Tube Store's descriptions and reviews are spot on.
As far as the caps, resistors, boards, sockets and whatnot goes, Amplified Parts is my usual go-to. They have a good selection and good prices. They also have blank & pre-drilled turret boards along with one's that have turrets installed. But if you get a blank one, you can print off the layout (make sure it's to scale) and just tape it to the board. That way you can install the turrets, caps, ect, the way they originally were.
This video briefly goes into a little detail about putting together a turret board. It's pretty straightforward. And yes, it's a different amp, but the construction principles are the same. Also, Tube Depot, from everything I've read, has some nice kits, but they are higher priced. Anyway, here's the link for the vid:
https://youtu.be/cEV1gluwcUM
ETA: But if you want to get your feet wet without the potential to shock the shit out of yourself, and build something simple, I'd start off with a pedal kit or two.