HELP, does a guarantor have to be a homeowner?

So I am trying to get a house for my second year at uni and I have paid my agency fee and love a house. Only thing is I need a guarantor and I'm struggling! I've got a friend who could do it but isn't a homeowner. Does she have to be one or will her wage and good credit be enough. The agency I'm going through is George Adams in Manchester if that helps.