Getting to the shops is a bit tricky. My 6 year old is eating the stuff non- stop so I’m about to run out.
The milkman can deliver it but it’s so expensive.
I remembered about 20 years ago in France I saw a machine that if you mixed a bit of normal yogurt with milk you could culture your own. And it seemed so straightforwards.
So I found a couple of recipes. If you follow them let me know how you get on.
https://www.theguardian.com/lifeandstyle/2014/jan/18/how-to-make-yoghurt-make-your-own
www.thekitchn.com/how-to-make-yogurt-at-home-cooking-lessons-from-the-kitchn-125070