I know a few family’s who have children with autism who have tried the cf/gf diet with mixed results. It is worth a try. There are a-lot of experienced parents on the special needs discussion thread on rollercoaster.ie it might be worth posting there. Good luck with it, hope it works for you.
Also the Louth/Meath autism support group meets once a month in the Laurence centre, I think they are meeting this week, lots of parents with experience to talk to there, I can find out about the support group meeting if you like, they have a face book page.