Yes, the Power of Attorney ceases upon death, but if you are named as an executor then the Power of Attorney effectively endures.
That's what happened when my mother died. All I needed was a few notarised copies of the Death Certificate, abtained from a high street solicitor. Then, after presenting my own valuation of the estate, which included her house and belongings plus a bank account. Once I received the cleared Probate documents after paying death duties, I was then able to distribute the assets according to the will. The whole thing took about five weeks. I did not, apart from the notarised death certificate copies, require the use of a solicitor. More than one copy is needed because each creditor or asset holder needs to see the death certificate at some stage, so I did not have to wait until each copy came back from the various parties. Saved a lot of time.