About 5% of CELTA students fail the course and another 3-5% drop out due to many reasons:
They underestimated the intensity of the course. When people tell you the CELTA is hard work, they really mean it. Lesson planning, teacher training, practice lessons and reviews back-to-back for 4 solid weeks PLUS the homework and additional reading. All of this, and you’re expected to maintain a healthy team atmosphere with tempers short, workloads rising and heaps of tutor criticism (that’s their job.)
Personal issues. Some people enter into the CELTA course while dealing with family problems, bereavement, breakups and other deeply personal stress. The CELTA course is unforgiving of personal issues and there is no leniency from the tutors.
But the CELTA is university-governed qualification and I’m afraid a fail is a fail. If you want to re-take the course, you’ll have to apply and pay again.