We have 3, living in a 4 bed semi (3 doubles one small double). Before the youngest were born we had a three bed terrace, but moved when the youngest guest was about 18 months as needed to move her into her own room, and sharing with her older sister wouldn't work due to the older one having autism.
There was a gap of 7 years between my youngest and middle, with only a gap of just over a year between middle and oldest. The elder two are adults now and my youngest just finishing GCSEs.
Space wise my eldest, boy, has the small double as he has less "stuff" and doesn't really mind.
I have a home office in an outbuilding in the garden, which is a godsend as we have become a fully remote WFH company. Converting the building cost a bit however I hate having my work in my home, and we didn't have space for an office inside, so when the office closed it was an easy decision.
I don't really want to give full income details, but I pay the higher rate of tax and lose a small amount of personal allowance. My husband earns a lot less, not much above NMW, and only works part time. However his money is really just for his fun spends. Our mortgage is also pretty low for where we live.
We are pretty comfy now but we didn't always earn as much. When the children were younger I was earning less than half what I do now. However it was enough to meet the bills and have a few treats without needing our income to be topped up, so my husband was a stay at home dad. That saved us needing to spend on childcare. If I hadn't earned enough to cover all our costs, we probably wouldn't have had a third as the childcare bills would have been crippling.