Think I'd risk a walk up, or keep looking for a reservation, including day of. Breadbox is nice, if you like that kind of food. And if hungry, Red Oven' pizza is tasty. Good bar type food at NBC Grill and the Hard Rock Cafe.
Your day is a Thursday, and I don't think the crowds will be as heavy. Many stop for a drink or so, but many just go right to the Studios, to be inside, to Stay and Scream just before 5pm. At that time of day, I'd think most would be younger families, and maybe some that had an early lunch, or used to eating at that, what I consider, early dinner hour, that would be your only others seeking dining at that time.
I will be there that day, Having arrived that Monday. I don't make many reservations, and usually do so, the same day, as I don't do many places that need a reservation, and I don't mind quick service places either. The only reservation I did make so far, is for SF's Cookhouse restaurant, as it partipates in the Orlando Magic Month promotion, and I knew the day I wanted to eat there, and enjoy that fixed priced dinner.
Have fun, and I'll be doing HHN the next night. I'm a one and done, as scary is not my favorite entertainment.
And oh, if you are doing HHN that night, if you want to join a private VIP group, I think Soniam still has room for another body, er person to join her group. You can check with her via PM or ask on this board. I think she started a thread looking for people to join.