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. For this info see:
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:
The history of the Black Cultural Archives is documented and discussed in Hannah J.M. Ishmael's 2020 PhD Thesis 'The Development of Black-Led Archives in London.'
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.