Guide
School term dates across the four UK nations
Updated
Any project that says UK school term dates has already made an assumption worth examining, because the four nations do not organise this the same way and one of the government's own tools stops at two of them.
England
The most fragmented. Section 32 of the Education Act 2002 puts the decision with the local authority for community, voluntary controlled and community special schools and maintained nursery schools, and with the governing body for foundation, voluntary aided and foundation special schools.
Academies and free schools sit outside that entirely and set their own. In an area with many academies, the council's calendar describes a minority of the schools.
Wales
Covered by the gov.uk term dates tool, which states it is available in England and Wales only, and which answers by pointing at the local council's website.
So the practical shape is similar to England: local publication, no central dataset, and the school as the final authority.
Scotland
Outside the gov.uk tool, which points to a separate resource. Dates are set locally through Scotland's councils.
The terminology differs too, which matters for anybody parsing published pages: assuming English vocabulary is a reliable way to miss records.
Northern Ireland
Also outside the gov.uk tool, which states it is available in England and Wales only and directs readers to a separate resource for Northern Ireland.
This site does not describe those arrangements further. The Department of Education page that would settle it refused our checker, and we do not summarise a source we have not read: go to it directly rather than trusting a second-hand account of it here.
The design consequence
Four nations, four publishing models, and no common schema across any of them. A system built around English councils does not extend to the other three; it gets rewritten.
Decide the scope before the data model, and be explicit in your own product about which nations you actually cover. Almost nothing on the market is.