My son has autism, he is 14 now so nursery was a very long time ago. I had him in a place that was a mainstream playgroup but had 6 places, specifically for children with additional needs. This worked well as there were special allowances made for him and the staff had experience of his needs.
I would look at finding a place like that, nothing worse than dealing with people that have no experience of autism and just expect them to settle and behave like the other children, I also don't like it that some use the naughty/time out chair for behaviour...a child with autism will not necessarily understand why they are there and make them more distressed.
I would view a few places, go with your gut. Ask what their procedures are for dealing with such behaviours, ask if they have previous experience and what outside agencies they have working with them, ie, occupational therapists, area SENCO etc.
Preparation is key in my opinion, if you send him, do short visits. Take photos of the premises (they won't let you take pics with children in them, they may do the photos for you) and staff so that you can show him at home.
Do what you feel, if you feel its not right for him or you then don't do it. People can be pushy because they think its for the best, without understanding how autism affects the childs ability to cope etc. Gut feeling is what I have always gone by xx