A remembrance service will be held at Canterbury Cathedral later as the UK observes a period of mourning.
Prince Charles said his father "would have been amazed by... the touching things that have been said".
People are urged to be considerate when non-essential retail rules ease in England and Wales on Monday.
An ally of Matt Hancock tells the BBC he "acted in entirely the correct way" after the 2019 meeting.
Thomas Schreiber is charged with murder, attempted murder and dangerous driving.