I think you don't have to since you studied there. It means that you past the standards.

If you got CAS and applied for Visa before July 2011, you ll be allowed to work during term times and full time in vacations. College students, or individuals of that same age group, believe that they will be just as happy as their parents but expect to earn less over their lifetimes. An AP poll was...

As far as I know, you can't get a visa. You must clear first your police record.