Sometimes, conservatoires will waive formal qualifications for mature students, but in other instances they may demand almost the same qualifications as they would from an 18-year-old. Usually, all applicants will need to display similar levels of practical ability, regardless of their academic qualifications; however, this can usually be demonstrated at audition or interview.
We advise that you talk to conservatoires direct before applying. You can check the mature undergraduates' section of this website for more information.