I see a bug on one of your caps. By the PT.........

You will need a decent soldering iron and a multimeter plus very basic tools. You should have some experience at soldering and be able to recognise a good joint from a bad one. You should print out the layout on A3 so you can mark on it each connection as it is made.  Other than that its quite straight forward. Be aware the small DPDT switches are quite fragile don't over tighten them as they will break!. You will also need a variety of sizes of heat shrink tubing. If you know what you are doing with valve amps (and I didn't) then power up first without tubes in to check the various voltages. I took mine to an amp tech who did that for me, installed the tubes and biased them (though I could have done that bit). Worth paying just for the peace of mind.

Be aware of the possible problem with the OT primaries. My OT had its wire colours incorrect and others have found a problem that OT was out of phase with the PI and squeeled like mad. Just need to swap the two wires over then you'l be OK. I don't know if theres a way to check this before powering up with valves in. Also get in the habit of checking the capacitor voltages before delving inside after having had it powered up. I'm generally finding there is no residual voltage even after only a few minutes, but its always safer to check.