I reiterate that you ought to check into the student visa/work permissions process again. I am here on a student visa and was told that this visa alone does not grant me permission to work.
Either way, good luck!
Update: I found the information I was looking for to back up what I said: (http://www.universidad.es/information_and_resources/during_your_stay/working_in_spain)
Below is a translation of the article from the 2000 Act on the rights and freedoms of foreign nationals in Spain, for reference:
Article 90. Employment of students and researchers.
1. Foreign students in possession of a student visa may be authorized to take on paid work, in public or private institutions, when the employer applies for a work permit and when all requisites listed under article 50, except for paragraphs a) and f), are met. The aforementioned activities must be compatible with the studies undertaken, and the income received must not be considered as the main means of support. It will not be necessary to apply for authorization for work placements in public or private institutions which form part of the study programme for which the student visa was granted, and which take place within the framework of the corresponding collaboration agreements between these institutions and the study centre in question.