Composted animal manure is the best (unless you're growing root vegetables), but you can also use good garden compost you've made yourself, or leaf mould, spent mushroom compost, anything like that. Hard to say how much you need, don't know the area size, but probably, for composted animal manure in bags from the garden centre, a bag spread over 6 x 6 feet, preferably 4 x 4 feet per bag if the soil is poor, but without burying the stems or trunks of any woody plants - these shouldn't have anything piled up round the base. If the soil's really claggy, claggy enough to make pots with, horticultural grit spread about would also be helpful - you don't need the same quantity as with the manure though.

Whatever leaves fall in Autumn and land on my property - that's my compost. I guess it depends which way the wind is blowing.

Did you intend digging the compost into the ground between you shrubs or herbaceous or spreading it between the plants? As suggested, if you are going to try and lighten you soil by digging some materials in the compost and crushed grit will do the trick. If you intend to just spread some animal manure or home-made between the plants then, I would wait until the spring as any nutrients will be washed away with the winter rains.