I'm very sorry for your loss.
If your husband was in receipt of a contributory pension, then you should be eligible for the widow's pension based on his record. My mother has recently gone through the same process.
In my mother's case, once the Dept were advised of my father's death, they arranged for the 6 week payment (paid as a lump sum by cheque), and started the process for her widow's pension claim, so that it would be in payment for week 7.
There were forms to be completed, the Department sent them out directly to my mother.
I suggest you contact the Contributory Pension section of the Department, they are very helpful.