You know it's just certain things you will be able to prescribe, not medicines in general? For instance Panacur cannot be sold in a petshop unless the person serving you is a SPQ.
My hubby is the boss at AMTRA (the people who regulate the training), you can find loads of info on the AMTRA website or the facebook page. As Goldmali says though it's not all medicines, it's mainly stuff like horse wormers and flea treatments like you get at PAH etc.