Sorry to hear of your loss.
This seems to be where you would contact for information on the plot. I took it from Liverpool's City Council website
Yew Tree Cemetery
Yew Tree is not managed by Liverpool City Council but by the Archdiocese of Liverpool. For enquiries relating to Yew Tree Cemetery you should contact the main office at:
LACE, Croxteth Drive, Liverpool, L17 1AA
Telephone: 0151 522 1000