My goal — Have a milk-replacement from some kind of canned milk, preferably without too much lactose.
(For what it's worth, I use this at work where I don't use milk frequently enough to justify a whole carton, but when I need a few tablespoons, I'd really rather have it available)
condensed milk — Works, but has a ton of lactose in it. Mix 1 part condensed milk with 1 part water.
sweetened condensed milk — avoid, it has too much added sugar to be a milk-substitute
[canned] coconut milk — Confusingly, this is a completely different product from refrigerated coconut milk. It's less good as a milk-substitute compared to coconut cream.