if you cant get any rabbit yet get some chicken wings, from somewhere like tesco, i buy trays for less than 2 quid that last a week, i just put 2 in a bag & freeze them, then get them out every morning & put them in the fridge untill they have defrostd.
If you want to feed some dry as well i would opt of a ferret food rater than a cat one, the cheapo cat foods are made with soya protein, the better ones are meat protein based but will cost more than ferret kibble, so if you have a decent pet place i would go there for the dry food