hmm could all do with one of those...
book depository http://www.bookdepository.co.uk/book/9780415253833/Writing-and-Difference £9.84 incl postage. looked at free (illegal?) downloads, but found a comment from someone saying that writing & difference was messed up.... found first 75 pages available on screen if you search google books. might have some more but they don't seem to want to upload.
cheaper at abe books and alibris (probably second hand). looked up on bookbutler.co.uk
I meant to tell you about aaaarg.org. You should be able to get a free pdf of it there.