July is NOT a great time to visit Orlando. It is VERY hot and VERY crowded.
As one web site says
"Unless high humidity, afternoon thunderstorms, and masses of hot and sweaty tourists sound like your ideal vacation, then avoid Orlando in the summer months (June to August)".
I went in February a few years ago for two weeks and we had weather into the 80s and low crowds. Their "winter" is like our summer, and their "summer" is like a sauna.
Walking round theme parks and queueing in that heat is no fun at all.
Unless it is too late I would cosider moving your holiday to another time of the year.
More here:
http://www.tripadvisor.com/Travel-g34515-s208/ Orlando:Florida:Weather.And.When.To.Go.html