Prioritise getting their beds set up as soon as possible. If you manage to get the keys the day before the move then dismantle their bed frames and go build them at the new house, they can spend the last night at the old house on mattresses on the floor. Roll their bedding up and put it in bin bags, clearly labelled, then put mattresses and bedding straight on the bed frames when you get there.
Label boxes clearly as you pack them with room and a general description of what is in them, e.g., Kitchen, Pans or DC1 room, books. There is nothing worse than needing something specific in the kitchen and being faced with a dozen sealed boxes that all say "kitchen" but no other information.
In a basket or open box put the kettle, cups, teabags/milk/sugar, a bottle of squash, biscuits. Also put in a torch, some basic tools (hammer, screwdriver, spanner), batteries, a couple of lightbulbs, any medications you need, and your phone chargers. That box goes with one of the adults and is put straight on the bench in the new kitchen.
When packing up wardrobes, leave the clothes on their hangers and pull a bin liner over them like a garment bag (put a little hole in the bottom to pull the hooks of the hangers through. At the other end they can be hung straight up and the bags removed.