Nursery school

Hi,

My 4 year old grandson is due to start the assessment process for possible ASD in a few weeks time. We think it’s highly likely that he has Asperger’s. He is a very loving and intelligent little boy with keen interests in satellite dishes, tv aerials and electrical plugs. 
He has been attending a mainstream nursery school for the last 2 years and this had been going relatively well until the last few months.The nursery staff are currently struggling to cope with some of his behaviour. For example, he has a habit of tipping out all the boxes of puzzles and other toys all over the floor. He also finds it very difficult to sit still for longer than 30 seconds. We think he has sensory processing issues and is quite restricted in the foods he eats. The nursery staff have very little understanding about ASD and are trying to impose their own boundaries and complex reward systems which I feel are just making his anxiety worse. 
My daughter (his Mum) and I are due to have a meeting with the nursery staff next week to try and discuss how we can all work together to support my grandson in his last term at nursery. Does anyone have any suggestions as to how we can help them understand what might be helpful for him? Thanks