Can i make the executor disclose the will to me if i know that i am included as a beneficiary, if so how?

My father dies at the beginning of the year and his partner has refused me and my brother access to the will, my father told me that I was incldued in the will. It has been three months now and she still hasn't recgistered for probate, What can I do to force her to disclose the will to me? I live in the UK