In the U.K, there are three languages besides English which enjoy, to some extent or another, minority-language medium education.
In Wales, there are Welsh medium schools throughout the country where all education (besides English classes perhaps) is through Welsh. In some areas, children have to travel a very long distance to attend English-medium schools. Many (most?) students at Welsh-speaking schools have English-speaking parents and don't necessarily speak Welsh as a first language, but by the time they leave school they are fully bilingual. Welsh is the language of administration and social activities at most Welsh-medium schools, but I believe there may be a few bilingual schools which provide both Welsh and English medium education. At post-secondary (16-18) level, there are AFAIK no 'Welsh-only' colleges, but at some colleges most subjects can be taken through the medium of Welsh. At university level, Bangor and Aberystwyth universities offer a range of subjects which can be taken entirely through Welsh, and both languages can be used with the university administration. However, the majority (but not all) social activities take place through English, as this is the first language of the majority of students.
In Scotland, there are some schools which provide GME (Gaelic Medium Education). This usually means that the first 2 years of education are entirely through Gaelic, and then English is gradually introduced until half of subjects are taught in English and half in Gaelic. However, with a very small number of exceptions, GME is provided in 'units' within bilingual schools which also provide English medium education. So, as a result, the language used on the playground is English. The range of subjects available through GME depends entirely on the teachers the school is able to hire- at some schools the range is very limited, at others it includes a number of subjects. There are only a tiny number of Gaelic-only schools in Scotland- only two that I know of (one in Glasgow, one in Inverness) and another tiny primary school which is technically bilingual but all students opted for GME, so is currently de-facto Gaelic-only. Providing Gaelic-only schools is difficult as most Gaelic-speaking areas are remote, rural communities which wouldn't necessarily be able to support two schools, one English and one Gaelic, and so GME is a compromise. However, GME units don't provide the same immersion experience as a Gaelic-only school. At post-secondary and university level, only a small number of courses are available through Gaelic. There is a Gaelic-speaking university institution called Sabhal Mor Ostaig which teaches a small number of degree courses through Gaelic.
In Northern Ireland, there are a tiny number of Irish-medium schools at primary and secondary level where everything functions in Irish. There is no Irish-medium university education AFAIK, but this is available in the Republic of Ireland, where Northern Irish students can study without restriction.