The nation manages it very well every Remembrance Sunday.
No, the nation remembers war, remembers the social, human and political costs of war, remembers the causes of war, and not individual people (remembering individuals is on an individual basis). PS: Remembrance Day is, in my view, unhealthy, so I wouldn't use it as an example myself.
I did not know any of the Manchester victims and therefore I cannot remember them. There is nothing else to remember, because their deaths were not a sacrifice, brave, heroic, an example, or anything else. They were - bluntly - murdered by a nail bomb in pursuit of a nihilistic ideology.
It is profoundly sad, but those are the facts. There is nothing to remember unless you knew the people themselves.