in my experience and opinion it is not necessary to go to a make up school. i have worked for 2 different cosmetic lines and really at the end of the day they want you to sell. i do have an aesthetics license and it might have been a plus but it wasn't what got me the job. i work at nordstrom and only 3 people outta 52 employees in the cosmetic department have any sort of actual training or license. & no one at the MAC counter has a license or extra non-MAC training. i'm not saying its a bad thing & it might be helpful for you but it's not necessary.
i dont know how old you are, where you live, or what sorta job you can get, but go to the counters and apply, the best thing to get is experience! thats really what they want. it might not be MAC at first but if you put some time in & get experience you'll have a better chance for the next time! do as many people's make up as possible, learn as much as you can and be positive! i've always noticed the people with the best attitudes gets the jobs! you'll do great & good luck!