Pack an overnight bag or bag for the first weekend with enough clothes to get you through including messy ones for being able to clean and move furniture etc, and a set of clothes for going to work on the first day back. I once moved flat, got interrupted when packing my clothes so dh took over. I had to ring work to say that I would be in when I had found a pair of trousers to wear - I had found all my tops but eventually found all my trousers in the very last box to be looked in, just before lunchtime...
Luckily my boss and workmates thought it was hilarious but I can imagine many workplaces might not be so understanding!
Also need to ensure that you have bedding for the first night, spongebag stuff, stuff for kids including favourite toys and things to keep them occupied, chargers for all devices, cleaning stuff, kettle and coffee and cups (or whatever you need for your drink of choice!), local map of the new area if you need it, list with all useful numbers on - solicitors, estate agents, banks, mortgage people, any trades people you might need like alarm person or locksmith, a large pack of loo rolls, a good, charged torch, a plug in night light...
and I'm sure there's more, but you get the gist of the sort of thing to think about!