Availability is not only your working hours. Time you have already committed — to a holiday, or to concentrating — should stop being offered to other people.
A booking slot is offered only when it is inside your working hours and nothing occupies it. So anything on your connected calendar removes that time from what people can book.
That gives you one habit rather than two systems: block it in your calendar, and Atwork respects it.
Days away are simpler still: add them as out of office, and they block bookings on their own, with no calendar event.
Open your profile menu, choose Preferences, then Working hours. Under Out of office, click Add range and pick the From and To dates.

Booking links stop offering every day inside a range. While a range covers today, teammates also see Out of office on your profile.
Do it before you announce it. Time blocked after someone has booked you does not cancel their meeting.
Block recurring time for the work that needs a run at it. A standing two-hour block that repeats weekly is the only reliable way to keep it — an unprotected gap in a calendar gets filled.
Setting a buffer on your booking links helps too: it stops meetings landing back to back and eating the gaps entirely. See Create a booking link.
A blocked slot simply is not offered. Whoever is booking sees fewer options, not the reason — the content of your calendar events stays private.
Teammates see an Out of office badge on your profile page while a range covers today, with the end date when you set one. People booking you never see it.
Check, in order:
Related: Working hours and availability · Create a booking link · The calendar