I'm next to useless at identifying wildlife in our wood, I really have to be working with them for a few eons to be confident. Now having spent the winter coppicing I'm fairly confident I can correctly identify all the species of tree I took down from their winter buds and the big give away when they leaf, (well it was only about six!) but better than I might have done a couple of years ago.
Anyway I've always found books a bit hit and miss for id'ing stuff, but someone recommended me the ispot website http://ispot.org.uk/ easy just take a photo post it and you can then have a heated debate about what it is!
Cheers
Rich