The whole trick is timing. Block the dates before your calendar opens that far ahead and nobody ever sees them, which means nobody has to be moved. A holiday decided in February for June usually costs you nothing at all.
Where people are already booked, contact them yourself and early, and come with dates rather than with an apology. 'I am away that week — I can do you on the Tuesday before or the Thursday after' keeps almost everybody. A cancellation with no alternative sends them looking elsewhere, and some of them will not come back.
Move your regulars first. They are the bookings you cannot afford to lose and the ones most likely to be flexible if asked in good time.
Say when you are back, in the message and on your page. The quiet week after a holiday is usually made of clients who assumed you were still away.
Then decide what happens to messages while you are gone. Either say plainly that you are away and when you will reply, or accept that you are working. There is no third option that does not involve answering messages by a swimming pool.