I hereby declare that, to the best of my knowledge,  [ student's name ] has completed all the courses and has earned all the credits required for High School graduation in this school. Therefore, [ student's name ] meets the High School completion requirement to enroll in college and/or university level classes. His/Her High School transcript will be issued in 30 days.

Fran, I really like this, but I have two small comments.  (1) Are you sure you want to capitalize "High School"?  It is not is not part of the name of a school.  I would suggest "high school", but possibly there is something I do not understand.  (1) If the transcript WILL NOT be issued until 30 days have passed, I would go with "...in 30 days."  If the transcript will be issued sometime before 31 days have passed (in two weeks, in 20 days, etc.), then I would choose "...within 30 days."

What do you think?