If you are still clearing fallen leaves from your garden remember they are a free and very useful garden resource. You don’t have to do anything other than put them into a bin liner or garden refuse sack, poke a few drainage holes in the bottom, put them somewhere out of the way and forget about them! Depending on the type of leaves and whether or not they were chopped a bit before bagging you could have wonderfully crumbly leafmould in a couple of years. It is an invaluable soil improver and makes an excellent mulch for vegetables, fruit trees and bushes.
A good thick layer over borderline hardy perennials such as some Penstemons will help keep them cosy over the winter. It is a good cover for bare winter soil, especially on the veg plot, where it will be gradually worked into the soil by the ever industrious earthworm. Running a mower over fallen leaves will chop them up and when mixed with a few grass clippings it speeds up the composting process to one year instead of two. But if you still have fallen leaves on borders around shrubs and hedges, leave these for the time being as they may be hiding hibernating animals such as hedgehogs, frogs and toads.