Haven't stayed at Bonnet Creek, so I don't know. I would call the resort, though. Most of the timeshares in the area have at least a few courts, so I would think they would have some. With so much to do in the area too, we've found that even at places like Cypress Pointe that only have two courts, we could get them whenever we wanted.
We are a big tennis playing family, and like to stay at the Sheraton Vistana Resort as they have tons of lighted courts -- nine are clay and four are something else. They even sometimes have some little tournaments for guests that we've played in.
If you find out that they don't have these at Bonnet Creek you are pretty close to the various Disney resorts. If you like clay you can always pay to play on the clay courts at the Grand Floridian. My brother and I played there twice on one trip when our resort didn't have tennis courts. He lives in Idaho and I live in Missouri, and we always look forward to playing tennis together on vacations when our families get together, so we were willing to pay a few $s to make that happen.