I’ve built a bunch of the Befaco kits and think they would work well for an introduction or anything from Thonk with a good manual. The Befaco mixer or attenuator modules would be a good place to start then work up to things like the Rampage and Muxlicer.
As long as you pick kits with good manuals your chances of success are high. It’s not that hard to make basic kits and get comfortable with the iron. Just start small and accept maybe the first build will have issues. Befaco has a happy ending kit where they will fix your broken build but by the time you post to Barcelona it will be pricey.
You don’t need much to get started. Don’t need an expensive soldering iron, just something with a decent sized tip that gets good contact. I like the chisel style tips so you get a flat contact with the pcb. Would recommend getting a holder like this to make it easier.
Good luck with your first build!