If you can find space for a compost bin this will be your best bet. It will be best in a warm corner, on soil, not concrete. Compost is very easy to make. Start now and you will be amazed how quickly it all rots down. Start with a few twigs at the bottom to improve air flow, then put all your raw fruit and veg peelings/waste in, plus teabags and coffee grounds, grass cuttings, clippings and trimmings from the garden, annual weeds (the "wet layer"), layered with dryer stuff - for example, straw from a guinea pig or rabbit hutch, torn up newspaper or thin cardboard, torn up egg boxes (the "dry" layer)- no shiny magazine pages though. Aim for layers (wet/dry/wet/dry) so you don't get a slimy mess. Never never use cooked food waste or meat or fish - cooked or raw - because that will encourage rats. I have had a compost bin in my garden for 30 years or more and NEVER had a rat problem. If you've got a tree in your garden, or you get a lot of leaf fall in the autumn, gather them up, put them in a black plastic bag, tie up the top then stab a few holes in for air flow. Put somewhere dry - shed or garage - and check in spring to see how it's doing. If it's dry and crumbly then it's ready. Spread across the top of the soil and let the worms do their job. This is the best free soil improver you can get. For something more instant, B & Q do bags of composted farm manure, ready to use, no weeds, no stinky smell - just spread across the top of the soil and let the worms dig it in for you. You can dig it in if you want to, but I follow a no-dig regime as I have a dodgy back! Good luck!