work vs education

So basically i work weekends and i booked a day off (consider i have never had time off or called in sick and i walked in the snow when most others called in) and they won't give me the day off for a uni open day. I need to work because my parents can't afford to fund me for anything other then basics like food, phone bills, pens ect is all me but i hate it, it does nothing but stress me out and make me cry. I don't know what to do. Do you think if i emailed the unis and had a day off school i could go look round in the week? (ps i have to decide what uni to firm by the end of this month due to a scholership opportunity and haven't had the chance to go to one of my choices at all so far which was where i was going in the day off)