Make one shared bathroom work for a small group
One bathroom can be enough for a small group when expectations are modest and the busiest moments are planned sensibly.
Look at the morning bottleneck
If everyone needs to leave at the same time, agree a rough order for longer bathroom use the evening before. There is no need for a minute-by-minute schedule, but knowing who must be ready first helps. On a quiet day, let the routine spread naturally instead of creating a queue because breakfast has been set at one fixed time.
Keep tasks that do not need the bathroom elsewhere where appropriate. Hair drying or applying make-up may be possible at a suitable mirror and socket in a bedroom, following equipment instructions. Do not trail cables through wet areas or corridors to create a makeshift station. If the cottage has no suitable alternative, allow more time rather than trying to force one.
Discuss evening use too if the group has a fixed dinner reservation or several children getting ready for bed. Moving one longer shower to another time may solve the problem more easily than accelerating everybody's routine. Keep the conversation about timing rather than personal habits, and leave enough flexibility for someone who genuinely needs longer.
Give belongings a small footprint
Use a washbag that can be taken in and out, especially when storage is limited. Avoid covering every shelf with one person's products. Agree how towels will be identified and hung using the facilities provided. Wet towels spread over bedroom furniture are not a useful solution to a crowded rail; ask about an appropriate drying arrangement if needed.
Leave the room ready for the next person. Clear personal items, deal with water on suitable surfaces as instructed and make sure the door is available when you are finished. Small habits make a larger difference than a formal rota. They also prevent someone being repeatedly left to tidy before they can use the space.
Decide whether it is enough before booking
For a short stay, one bathroom may be an easy compromise. For a larger group, particular access needs or a week with several early departures, it may not be. Discuss the actual arrangement rather than assuming friends or relatives will be happy with it. Choosing suitable accommodation is simpler than trying to solve a permanent layout constraint with increasingly detailed rules once the holiday has begun.