To teach in a primary school as a qualified teacher it is necessary to have gained qualified teacher status via one of the undergraduate, postgraduate or employment-based routes into teaching. It will be for the head teacher to decide whether a teacher has the necessary knowledge and experience for a particular role in the school.
The law also allows unqualified teachers to work as instructors when they have a specific skill or knowledge, where a qualified teacher is not available and again where the head teacher is satisfied that this person is able to properly fulfil this role.