Church

As an autism mom, I'm thankful for my ward (church).  They have been there for me even when I wasn't in a very religious place and wasn't seeking their support.  I have made some great friends, and they have made every effort to help me feel comfortable and for my kids to feel accepted.
It is very important, to ask for help from your church and not just wait for them to approach you.  If church is too much for you with your children with autism, reach out to those around you.  Ask your church leaders if there is someone who can sit with your children during services.  Would someone be willing to take them on a walk or to play with them outside when they are acting up so that you can get that spiritually uplifting time you need to be replenished for the upcoming week?
I have done the church thing several different ways:  My first ward called someone special to be Garrett's teacher.  (That was when Caiti and Jason were too young to know they had autism).  It was nice to have him there every week, and Garrett loved him.  We also had a couple older ladies who didn't have children, who would save us a spot and help us out.

In my current ward, I don't have people from church who work on an individual basis with my kids, but everyone knows who my kids are and try to give them the same chances to participate in their classes, etc.  On our first Sunday, I went into their classes and explained to their classmates that my children had autism, that they might act a little different or not talk to them, but that doesn't mean that they don't want to be their friend.  I asked the kids to help them out. The classmates have been very cute, and look out for my kids.  I have used our respite providers to sit with my kids at church so that I can pay attention; I also have left my kids at home with the respite providers so that I could have some alone time and get that spiritual break from the chaos in my house.  Both ways have worked out fine. 
It's just finding what works for you and voicing your frustrations or what can be changed to those in leadership positions at the church so that they can help make it a better experience for your family.
If you don't currently have a church to go to, I'm biased, but I love mine.  There are chapels throughout the world.  To locate one in your area, visit this website: http://lds.org/maps/index.jsf?lang=eng#x=find&m=google&lat=0&lng=0&z=2&t=3  It will give you the address/directions of your closest meetinghouse as well as the phone number of the Bishop of that ward.  I would call the Bishop before attending and let him know your situation so that the ward can accomodate any special needs your family may have.