'List of things to leave for your children when you die'

I'm looking for tips / advice / bite-size suggestions from accountants, lawyers, IFAs and so on on: 

"Exactly what details to leave for your children' for when you die.”

We want to help boil this down to the crucial ‘one-pager’ you must leave for your loved ones. 

Plus comments on the potential issues if your children have to go searching for your assets, lost pensions, proof of home ownerhip, gifts that might be liable to IHT, passwords and log-ins etc