Before the van arrives: parking, access and stairs
What slows a loading day down, and the prep that prevents most of it.
Loading days are rarely slowed by what is inside the flat. They are slowed by what is in front of the building: nowhere to stop the van, a lift that was never booked, a staircase nobody mentioned. All of it is preventable, and the prevention is cheap.
Parking is half the day
The single best thing you can do is hold a space for the van as close to your door as you can manage. Every extra metre between the van and the doorway is walked dozens of times, in both directions, at both ends of the move.
Some streets need a permit or a suspension arranged with the local authority, and lead times vary by council. If you tell us where the van will stand when you book, we will tell you whether that street usually needs one and how to go about it.
Lifts, stairs and the long carry
If your building has a lift, book it with the building manager for the loading window; a reserved lift changes the day completely. If it is stairs, count the flights honestly, and measure the tight turns if any furniture is large. None of this is a problem, but all of it is planning.
Your quote asks about access at both ends for exactly this reason. Answer it precisely and the day is planned around the truth; the crew that arrives is the crew the job needs.
When the job needs more hands
Multiple floors without a lift, or a long carry from door to van, is honest physical work, and extra loading crew is available as a paid add-on, arranged in advance. What makes it work is the phrase "arranged in advance": tell us about the fourth floor when you book, not when the van arrives.
And if anything changes between booking and loading day, the building works, the closed street, the broken lift, one message from you is all the re-planning needs.