Thanks for all the input guys. I revised my letter according to what smarteyeball
wrote (I didn't get to read the other replies after that since I went to work already >_<), and I think it went pretty well. Our HR manager even wanted to introduced me to one of our bigger store's HR Manager. I don't know what's that for but she gave me some advice about school and thanked me for being very professional.
They said I could always come back should I need to. :>
P.S. I think I should've wrote what jfar said XD XD XD