Note you will also need to contact all the companies the decased dealt with to make sure he does not owe them money, or they owe him money, and to close off the accounts.
This can be the gas board, electricity board, water board, council tax people, phone companies, insurance companies, banks, stocks and shares (if he has them), premium bonds, insurance companies, benefits office and probably others I have not though of.
If he is paying by direct debit, or if he has paid for something in advance like insurance, they may owe him money.
But with things like tax or other benefits he may owe them money.
This all has to be sorted out before you can distribute the remaining assets.
It can be a lot of work.