If it's any help, Angela Carter's correspondence is kept at University College,
University of London. The address is:
     University College Manuscripts Room,
     The Library,
     Gower Street,
     LONDON
     WC1E 6BT
I don't know whether they also have the manuscripts of her books.
                                                     Richard Myring
                                                     (Archivist)
                                                     University of Salford
                                                     SALFORD
                                                     M5 4WT