I like the notion of 'unobligated' in that it stresses that, for this instance, in school one's readers are obligated. With 'volunteer' I don't feel that condition is evoked; in fact, I can imagine people volunteering to read one's as yet unpublished work, but still feeling obligated to volunteer as a friend. But 'unobligated' is a mouth full of tongue to say, and if it should express freedom and willingness then it should lyrically sound that way. 'Volunteer' accomplishes that part, but leaves me wanting to tack on another qualifier.

Oh Friday morning.