Has the school performed any testing on your son? You have to sign a paper allowing them to do the testing, so if you have not signed, they have not done. If they have done, you should write a letter to the spec ed department requesting that you receive a copy of the results of this testing prior to the meeting. Put it in writing and hand-deliver the letter to the sped department, ask them to date stamp it and give you a copy. You have the right to receive those reports I think it's 2 of 3 days prior to your team meeting. This will enable you to see what their results are. You won't walk into the meeting without knowing a thing.
Have they determined that your child will be placed on an IEP or 504? The first part of the IEP is the vision. Prior to an IEP meeting, you should think about what your vision is for your child in the next year.
Generally, the meeting is chaired by the team chairperson. The child's teacher is there. The school psychologist could be there. Basically, anyone who has performed testing on your child should be there. If your child requires speech therapy, the speech therapist should be there.
I will tell you that we all want to believe that the school systems know best what a child needs, and they will give that child exactly what they needs. However, budgets prevent this. If they can save, they will. You have to be your child's advocate. Every town should have a parent advisory council (PAC). I am from Peabody, and our PAC has monthly meetings with informative speakers regarding all kinds of subjects. We are required to provide a basic rights workshop yearly. You should check with your town to contact the PAC officers to find out about meetings. I have become very knowledgeable about what my child, who is 17, needs through networking with other parents, being an officer in the PAC and attending meetings.
A good source of info for you would be the Federation for Children with Special Needs. No one knows your child better than you. I have learned that parents must be advocates for their children to insure that they get the best possible.
Contact me if I can be of help.