I'm sure my mother used to make this, mainly to use up milk that had gone off. This was in the days before most people had fridges. No heating of milk, or lemon juice, or buttermilk required. Presumably you could still do it this way. Just get some milk and let it go off and then strain it through muslin. Or you can get pots to strain it.
I imagine this is how cheese making started. It would have been the only way of storing milk in those days. Excess of milk in the summer would have been turned into cheese to eat during the winter. Cottage cheese is only the early stage of the process.
One can get unUHT'd milk in most supermarkets. Generally it's not with the other milk, but probably near the butter etc. 'Lait frais', blue tops or red tops. Or if one happens to live near a farm that has dairy cows, you might be able to get it direct from them. Or goats milk. Take a bottle with you.
I've been getting goats milk fromage blanc from the local market. They call it 'faisselle', which actually I believe is the word for the pot they strain it in. I have seen cows milk faisselle, but it's not as common, and anyway I prefer goats milk. So if you see a fromage de chevres seller in the market, just ask them. They may have some out of sight in a cold box.
Phew! I thought that was only going to be a quick post.
P.S. Fromage blanc isn't as curdy as the cottage cheese you're used to, but I prefer it.