You should set up a new account with the bank, not necessarily the same Bank as your father's bank. You will need all the paperwork and identification for both parties - passports will be accepted, but you may also need to produce utility bills to prove the addresses. A cheque book will be issued with both names on it, e.g.
"Frank Smith attorney for Jack Smith" ( or words to that effect). You may use this to pay only what he would have paid himself. This account should receive his pension/s and possibly the earnings from investments.
When the father dies, this account can no longer be used. The bank will close it, and will only release the money when probate has been granted. In some cases, a bank may honour cheques from the Attorney account for funeral expenses. Check this with the bank concerned, as not all will do so.
Do keep checking with the website of the Office of the Public Guardian.