As we are members of Woodland Trust,we were sent a handy little booklet on tree identification. The booklets are very good so invested in some of the others - fungi, flowers and butterflies. They are ideal if you can get a copy of them as the pictures are pretty good and contain info such as leaves and winter twigs for the tree version and edible as well as poisonous fungi in one of the others.
Heres the link
http://www.woodlandtrustshop.com/books/leaf-swatch-book