It can be very boring working at the Front desk as a volunteer. A lot of the time, there will be very few visitors coming in or no courier jobs needing completion for hospital staff. It's easily fixed by doing homework or reading a book.
Also, if you're looking to really enter the medical field, this isn't really to right volunteer work for you. You're better off just shadowing a doctor.
There's also a lot of volunteers just like you, so you might have some difficulty if you're trying to acquire more hours. They even put 3 volunteers at the front desk on weekends for a 2 hour shift because there's just so many volunteers!