Many people who start an apprenticeship or traineeship have not done any post-school education. This is particularly true amongst young school-leavers.
However, recently we have seen an increase in adult and mature apprentices and trainees, and young people who complete a vocational qualification either at school or prior to starting an apprenticeship or traineeship. For these people it is important to keep in mind that you can't re-do the same vocational qualification once you have completed it.
This means that if you have done a certain certificate or diploma, you won't be able to do the same one as an apprenticeship or traineeship. For people who want to do some training before starting an apprenticeship or traineeship, this is important to remember.