Rapid electronics still sell leaded solder.
www.rapidonline.comThe US still use leaded solder (as I expect many other countries do), and as leaded solder can still be used by some industries in the UK and can still be used for repairing old equipment containing leaded solder it should be available for the foreseeable future. If you really want to push the boat out try the Future HF silver loaded solder (62% tin, 2% silver, 36% lead) as this is even better than 60/40 (due to its lower melting point at eutectic nature). We use this for all work now.
If you going to use the lead-free solder then you really need a 50W temperature controlled iron, such as the Weller Magnastat, and use at tip temp of around 425°F/220°C rather than 370°F/190°F. Trying to use a 15 W cheap effort is hopeless, and you really risk damaging your work.
I love lead.