I am about to send my autistic son to a special preschool and I am a nervous wreck?

My son is about to turn three in April. He will begin a state funded preschool at that time. He will be going to a public Elemantary school for 5 days a week for 6 hours a day. I am apprehensive about this because he is uncomfortable around people he doesn't know and has never been away from me and his dad. I worry about the teacher he will get and whether she will understand his needs. My son has feeding issues and still relies on milk as his primary source of nutrition and I worry that she will take his bottle away. The tough love approach is ineffective on him. I worry that he will have contact with the regular students who are not in the program. He cannot communicate with me to tell me if someone is mistreating him. Does anyone have any experience with this type of program? How did your kids do? Any advice is greatly appreciated. Thanks.