Letter of wishes would be the nearest cover I would think; however any property of value has to be listed in the CA24 as there may be inheritance tax to be paid.
The letter of wishes doesn't replace the will/probate/ administrator process; but allows you to let family and friends have momentoes, small items of low value, household goods (family china from Grandma), mom's wedding ring and the like.
Try and keep it simple.
I had to do similar for a deceased relative and it took me six months to locate and distribute everything.