My father was british but lived in Greece He died last year and had a greek will. His wife, who isn't my mother will not give me a copy of his will. How can I obtain a copy? She is also from britain.

Were they both living in Greece? Assuming the will is going to be probated in Greece you really need to ask the court for a copy or hire an attorney there to follow up on it.

A simple search for probate attorneys in Greece found many, here is an example

Wills and Probate - LAWYERS IN GREECE ATHENS GREEK LAW IN GREECE

ATS Law Office Greece - English speaking - Greek Family law - Inheritance - Real Estate law