I’ve just bought a recipe book about fermenting and it is talking about Kefir milk grains it sounds like a yogurt culture. I had a yogurt culture but it needed a machine to get the temperature right. Kefir sounds easier is it?
You don't need a machine to make yoghurt.
An airing cupboard, a vacuum flask or other suitably-insulated container does fine - with a thermometer of suitable range if you're feeling anxious about it. I've used a heated seed propagator, too, to keep a jar at a suitable temperature.
Kefir is only easier to make in that it doesn't need this level of additional warmth; however be sure you like the flavour before trying to make it at home. It uses a bacterial culture (the kefir 'grains') which produce butyric acid, so a very different flavour from yoghurt which produce lactic acid. Personally I think it's horrible - it tastes of vomit to me.
BBC Good Food has quite a good article on it
here.