I would start in your garage, empty it onto the drive, and then pack up its contents. Stack neatly back in garage.
Now you have somewhere to stack your boxes.
Next the loft, then pictures and ornaments.
Then work out what you need to use up untill moving day and what can go in boxes now and do them in that order.
Write down what you are putting in each box and label it! So if you need to find something you can!
If your DC are young get them involved by packing a first night box for themselves, with PJs, washbag, a book and dvd and one or two toys, and clean clothes for the next day. That way hopefully they will be looking forward to opening their special box and playing with its contents, and you won't have hours of "Muuuum wheres xyz?, Muuum I can't sleep without xyz"
Last box to pack is the one with the kettle and tea bags.
No idea about chickens, could they maybe go the day before? Or first thing moving day before the vans start coming?