You can ask your agency for a gig from your calendar: pick the date, the times and the room, and say what you're after.
A request isn't a booking. The agency confirms it and finds an act, and it becomes a booking once an act accepts. You'll see the status change as it moves.
The more specific you are about the kind of act and the audience you're expecting, the better the match. "Something for a 40th, mostly 80s, no full drum kit" gets you a much better result than "a band".
If you have preferences about which acts you do and don't want, tell the agency; they can record them so future suggestions reflect it.