Adafruit Mini Solder spool - 60/40 lead rosin-core solder 0.031" diameter - 100g
If you want to make a kit you'll need some solder. This 100g (about 1/4 lb) spool is just the right amount, not too much (like 1 lb spools) and not too little (like those little 'pocket clip' vials). 0.031" diameter, 60/40 'no clean' rosin core. Good for all through-hole soldering and some larger SMT soldering (especially when used with wick).
This solder is not lead-free, but that's OK for European/UK customers as long as its for personal use only - no production use.