you regret not doing better when you were at school. It may have been years since you left school. You had a hard time working and surviving in life. You had thought about your past and wondered if you could have done better in life, had you done better in school.
Dreaming of school has an underlying meaning. You are anxious about your present life. What can you do when you see this type of school about your past? You can reflect on your present life and what you can do to improve your situation. You may not be able to return to school to further your prospects. You can look into what you may be able to do and start working on those areas.