Library Hub Discover will find you books in other libraries in the UK (plus Dublin).
Library Hub Discover does not tell you which of the libraries it lists you can access, or how to arrange a visit. For this info see libraries in London.
The key libraries indexed by Library Hub Discover include:
And the following may also be useful for African art:
Two key libraries are not indexed by Library Hub Discover:
WorldCat will find you books in other libraries worldwide. Coverage is uneven; e.g. there are some major African cities with no libraries included.
The SIA librarians will help you find books and access libraries anywhere in the world: though please note our knowledge of many countries is limited.
The Metropolitan Museum of Art in New York has produced a database of books about African-American artists in its library.