I agree with everything BowlingBun has written.
The Organ donor team gave me the telephone number of the Compassionate Friends, an International organisation started in UK for parents who have lost a child(and siblings and grandparents).The phone line is manned by bereaved parents,and when I phoned,within 24 hours of Rhys's death,could not believe this lady I was talking to,was able to find a reason to get up in the mornings. It helped so much.
Something else that I wished I knew more about, is the inquest.While the clerk was very compassionate,I was not really kept up to date with things that were going on,and no idea at all that the NHS would have an interest in it,and would make me feel as though I was on trial.
Even after the inquest, we could not collect a death certificate until my son's death had been authorised elsewhere,which could take up to a month.(his death had occurred over a year earlier, so it had to go very high up.)The Coroner's clerk had told us that it would be available within days.
At a traumatic time,a bereaved family is often expected to understand and know everything.
One of the things that is a struggle with a sudden death is the disbelief. I still can't believe it at times.
Accept all the help you are offered, it is usually being offered because people care. My elderly next door neighbour asked her cousin to stay with her the day of the funeral,so that she could have our dogs in there for the day.She also sent a meal in to us one evening,already cooked,complete with lovely fresh fruit and cream for dessert. It was the first time we were able to actually taste food.
Keep any condolence cards to read through at a later date. I read ours after a year,and was so surprised, there were many people that I didn't realise we had heard from,and it helped after a year to read their thoughts.
(I know these things aren't very practical,just what helped me).
Also,and the biggest, biggest thing to remember if you have children.They have also lost a close family member.Siblings are called the "forgotten" mourners and I read of so many who believe their parents do not love them any more.My two children still here with me have become even closer since their brother's death,but I still worry very much about both of them for their future.