Thats interesting where did you get the rennet I want to make some goats cheese. You need fresh milk for cheese normally.

Hi Stuandeve.
Overheating or UHT treatment would not prevent the milk from splitting into curd and whey (liquid). UHT treated milk will not taste nice. Did you by any chance use low fat milk?

I would have to see exactly what you did before I could make a definite comment. However you can make a nice curd type cheese called Paneer  without using rennet, heated milk is split using citric acid/lemon juice/vinegar and strained through muslin and pressed. This is vegetarian cheese and it is used in cooking in India, currys etc.

Yes I know Halloumi. I used to export large quantities of it from Cyprus into the Middle East years ago. The best quality is made from Sheep or Goat milk with Mint leaves and is stored in salty water. It is good for cooking. You have to use rennet to split the milk, I think they used to heat up the curd after straining then make into patties and store in salty water. We used  Cows milk and packed it in half pound flow packs with salty water and mint.
There is a cheese available in supermarkets in Spain "Oveja Curado" it comes in KG or 500gm rounds, about 10euro a kg. it fries up like Haloumi if you add a little mint it is slightly similar.

The curado is not exactly like Halloumi  but it browns nicely on the surface and does not melt all over the pan and with a little bit of mint it has a nice rich taste. I used to be a cheese buyer I traveled all over choosing cheeses.