Pack away anything you don't need every day as you cannot imagine the dust until it's too late!
Will you have a kitchen / fringe freezer?
If you already have quotes or an agreed builder, make sure you have or have access to 20% contingency fund. Especially in an older property, they cannot predict what they are going to find/not find.
Depending on when they are starting, if in winter buy a couple of electric heaters. We were unexpectedly without heating for a weekend when plumbing went wrong on a Friday afternoon - with only sheets of plywood between us and the outside - our kitchen was 8degrees!
Expect it to take longer than they are predicting.
Buy cheap mugs for the builders to use - I bought 5x £1 from Asda and glad I did as they get left in all sorts of places and used with cement covered hands etc!
Set boundaries in the beginning if you need to - eg if they can or cannot use your facilities, loo etc. No shoes if going on carpets (unless being replaced!),
Ask questions, if you are not sure ask - it saves bother in the long run. If you're unhappy, shout it out (not literally) but don't be afraid to speak up - it's your house and you want no regrets.
Use their expertise though, they will likely have done some things a million times, but it's new to you - they may be able to help with decision making that seems daunting at first - like light locations, or paint types etc!
Good luck!