Use Class C2 (residential institutions) relates to residential care homes, hospitals, nursing homes, boarding schools, residential colleges and training centres. This use class also has a sub category C2A for 'secure residential institutions' including prisons, detention centres, custody centre, secure hospital or secure local authority accommodation.
Use Class C2 (residential institutions) can benefit from limited permitted development opportunities to change use without requiring a full planning application. There may be conditions and limitations to such a change however, and further detailed information about this can be found here on the Planning Portal website. This website also details other restrictions to permitted development that may be in place, such as planning conditions or Article 4 Directions, and it is recommended you get confirmation from the local planning authority about changes of use proposed using permitted development rights.
If a C2 premises does not benefit from permitted development rights, planning permission may be sought to change it to another use. You can learn more about this process here.