[davegardner]

You can certainly use UHT milk to make cheeses that don't contain rennet such as paneer, ricotta, and quark. Some argue that you can't make good quality versions of these cheeses with UHT milk. From personal experience, I've made quark with UHT milk and it seemed pretty good quality to me.

I do get excellent results making yoghurt with UHT milk. It's also a simpler process as there is no need to heat the milk first before adding the starter.