Get 2 files of some sort to hold all the manuals, instructions , alarm code etc - one for all the stuff you are leaving, and one for the stuff you are taking.
Maybe a new home card and wine for your buyers.
I think we tipped £10 per person per move (into and out of storage) so would budget £20 each for a single move - hand it to the foreman to share out, but do it in sight of the men, so they know it's coming. Plus a supply of drinks and snacks.
If you are dropping off keys to the agent, take a break in a local cafe then, so you aren't hungry when unpacking.
Reconfirm with the agent how to collect the new keys.
Bring wipes, bleach, spare lightbulbs and loo roll.
Mentally prepare yourself for the new house feeling, looking and smelling less than perfect now that it is empty. It may take a few days until it feels like your home.
Good luck!