The biggest practical challenge in a shared house is timing, all housemates typically need to have moved their belongings out before the clean can properly cover the whole property, which means coordinating everyone's individual move-out dates against a single clean booking.
Splitting cost fairly is worth agreeing on early, generally either an even split regardless of room size, or a split weighted by room size and shared area use, decided before booking rather than after the invoice arrives.
It's also worth confirming who's responsible for booking and being available on the day, since property managers will hold the whole household jointly accountable for the final result regardless of which individual tenant organised the clean.
