A family holiday is not a kind of destination. Almost anywhere that suits an adult can be reached with a child; what changes is everything arranged around the journey.
Three of those changes are legal rather than practical, and they tend to bite in that order. Consent comes first: taking a child abroad without the agreement of everyone with parental responsibility is a criminal offence rather than a courtesy, and the rule is drawn differently in Scotland from England and Wales. School terms come second, compressing British family travel into a few weeks a year behind a penalty regime that was rewritten in August 2024 and still differs in every nation of the United Kingdom. Carriers come third, and the age bands they work to — infant, child, young person — are partly fixed in law and partly invented, which is why two airlines can treat the same eleven-year-old quite differently.
The rest is logistics, and logistics is where travel writing ages fastest.