Sam, I think you could speed things up by separating the leaves from the rest. Leaves (from trees) take, as far as I understand, longer to break down than mowings, kitchen stuff, etc. You could make a leaf 'bin' out of chicken netting and leave for a year or two, or a large plastic sack with lots of holes in it.
Palais glide, a friend of mine opened her dalek type bin in September and found a large rat looking up at her. I have not had that experience with my 2 dalek bins, but they are on very compacted ground. It is good, I think for the bins to be in contact with the earth rather than resting on paving stones, but you could put a couple of layers of chicken netting down to stop rats.