I have just completed (yet another) international move on my own while working almost non-stop for the 3 weeks running up to the move out date - I had also planned to get it all done when I had “lots of time” but alas, that didn’t happen.
Obviously it was less stuff than the house contents of 5 people, but the key really is decluttering. Be ruthless. Whatever can’t be thrown in the bin, place in large bin bags and take to the skip on the 26th evening / 27th. I had slowly donated some stuff but just on my last day I somehow produced 8 medium bin bags full of crap headed for the bin. (In all fairness I only ever do this when moving!)
Take one hour today to make everyone a “holiday” suitcase, out of which you will live between now and moving day. Again, be ruthless. You only need clean clothes, toiletries, perhaps some favourite toys for the kids, chargers and devices, things like hairdryers, toilet paper can also be left out.
Pack everything that isn’t those 5/7 clean outfits, main bathroom and kitchen. Tell kids they don’t have unlimited access to toys and books between now and the move, that’s just how things are this week.
Line up suitcases in the hallway and put everything in the rooms in boxes. Room by room, don’t be tempted to reassign contents or think “now would be a good time to also pack Charlie’s books as I’ve just finished Lucy’s so I know all books are done”. Nope, go geographically. Carrier bags are also good if you want things to feel less “finally” packed than in boxes - you’re using a van so it doesn’t matter how the smaller things are packed as long as they can be thrown in.
Do the kitchen second-to-last. Throw out all very-out of date canned food (ask me how I know), throw out all those little glass jars you’ve been keeping for the kids’ arts and crafts projects.
Bathroom is done last as you’ll need to use the loo and wash hands at the end of the move, so leave one or two hand towels out along with soap and cleaning products (+ the hoover and mop).
You can do this OP, but be very strict and get the kids involved in packing their own boxes if they’re old enough.