Process and cost factors
Living with a single bathroom during a refit

The short answer
In a house with only one bathroom, the refit affects daily routine directly. Planning around it in advance makes a noticeable difference to how manageable the job feels.
The moving parts
Agreeing which days the bathroom will be completely unusable, versus partially usable, helps with planning showers and toilet access elsewhere.
A downstairs WC, a neighbour, gym membership or a nearby relative are all realistic short-term fallback options worth arranging ahead of time.
Fitters can sometimes sequence work to leave a working WC or basin connected for longer, even if the rest of the room is stripped out, worth asking about at quote stage.
Clear communication about daily start and finish times helps a household plan around noise and access rather than being surprised by it.
Questions to ask any fitter
Agreeing which days the bathroom will be completely unusable, versus partially usable, helps with planning showers and toilet access elsewhere.
Questions we get asked
Can the WC stay connected for part of the job?
Sometimes, depending on the layout and where pipework runs, it's worth raising this specifically when the job is being planned.
How much notice is normally given for days with no water at all?
A competent fitter will flag any day with a planned isolation well in advance, since it affects the whole household.
Questions about living with one bathroom during a fit?
A short phone call usually answers more than a long email thread. Ask anything, including the awkward questions.