Lily recommends
Writing Down the Bones: Freeing the Writer within (Pocket Classics)Writing a Novel (Teach Yourself - General)
Writing Down the Bones: Freeing the Writer ...
by Natalie Naimark-Goldberg

People often ask me how to get started writing. My answer is always: read Natalie Goldberg's Writing Down the Bones.
Writing a Novel (Teach Yourself - General)
by Nigel Watts
£5.70
Nigel Watts is also good on structuring your novel.