Op, my deepest condolences. My niece died very suddenly 6 mths ago, it eventually was confirmed as a Sudden Adult Death but that initial shock is indescribable. I still cannot think of that evening, when my brother rang, without feeling intense pain and disbelief. She was found in house, unexplained death, police attended etc. I still dont think it has hit home yet, for me but certainly not for DB and SIL. Feels like a nightmare that we will wake from.
On a practical note, the initial PM was inconclusive and it took many weeks for a final verdict, which delayed the funeral. However, they were given an interim certificate from Coroners office, which allowed them to do the Tell us Once service and start to close bank accounts etc.
Take whatever help you can get - my SIL is from an Asian country and they got great support from that community at weekend and evenings, but nothing on the first weekdays. As their closest relative, I went to stay closeby for a few days and although they had meals brought by others, I did feel that just being there, being able to shop for them, listen to them talk about her, was useful.
Big hugs, I am in the North West if you are anywhere close