An author who decides to establish their own imprint by individually registering with an ISBN agency has a legal obligation to deposit a print copy of their book with the British Library within one month of publication.
Further information can be found at
The five libraries listed below are also each entitled to a free copy. You can either wait for a request or contact the Agent for the Legal Deposit Library at the Bodleian Library
The five libraries are the
Cambridge University Library
National Library of Scotland
National Library of Wales
Library of Trinity College, Dublin