Wow, Thanks Tony Newton for your full reply, though as a complete novice some of it was lost on me.

I see your point about it being a cold compost heap, and yes it is open to the rain to perhaps I should cover it with tarpaulin?? I'm not too bothered about how long it'll take to break down, but should I still add food scraps to it if it's a cold heap, and if so, will it be a prpblem if the food scaps become larger than the garden waste material in it?

horse manure, my horse is on untreated grass, so if I add it to my cold heap will it help?

Many thanks indeed.