You can't really tell them how to do the job - they will pack the van according to best use of space and safety, and making sure your furniture doesn't get crushed etc.
I have bought and sold and moved on the same day 4 times now.
This is probably how it will work:
Night before - put your bins out and/or or park your car across 2 spaces to create space for the van. This is v important!
Very early - removal co will arrive. They will start to move like lightening, moving through the house with huge pieces of furniture. IF they empty a room you will be able to clean in it. there will be very little that you and DH can actually do, in reality, and it is important that you don't get in their way.
Late morning / early lunch, 12pm at latest, because you will have been warned to be ready to complete by 12 - van will be packed.
You will now spend quite a lot of time on the phone to your solicitors finding out if you have completed. The solilcitors will have gone for lunch. The removal van will drive off to your new house and they will go to the local cafe and then wait outside the house. You could finish cleaning at this point. Eventually you will get the call that you have completed. Lock your old house - it no longer belongs to you. New owners will be waiting outside in van! Go to Estate Agents to collect keys, go an unlock new house.
Removal men will now move like lightening once again. It will take a surprisingly short space of time. If they are a good co they will assemble the beds for you. You CANNOT have a professional cleaning company in the house at this time. You will be busy answering questions while doing yor best to keep out of removal men's way.
Mid-late afternoon Removal men will leave.
Call for takeaway.
Go to bed.
Clean cupboards before you fill them as you unpack over the next few days.