
The site for fern enthusiasts
There are plenty of books and internet resources to help with identification.

The Fern Guide :A Field Guide to the Ferns, Clubmosses, Quillworts and Horsetails of the British Isles is probably the besp place to start. A thin paperback it easy to carry in the field and walks you though a well illustrated key.
As a field key this is perfect, but the only thing pteridologists love as much as a fern is fern books, and there are plent of other publictions that can help with identification.

Although titled as a field guide this is more of a desk guide and read at home book. Full of excellent colour photographs, this comprehensive guide covers everything you are likely to find in great details, along with plent of other useul information and characteristics.

Although no longer in print, this excellent book, with sihouette drawings and comprehensive characteristics is invaluable as both a field or lab guide. Highly recommended.