In case you aren't aware, you can get financial help if you have to arrange a funeral:
Funeral Expenses Payment (also called Funeral Payment) to help pay funeral costs if you get certain benefits - eligibility, how to claim, form SF200
www.gov.uk
Also, although the deceased's own bank account(s) are frozen until a grant of probate or representation has been issued, which can take months, banks are allowed to pay the funeral director's invoice (and inheritance tax if applicable). Funeral directors are supposed to explain this to people. Banks, etc. have a 'bereavement department' who will explain the procedure.