Leaving an autistic child

Hi all. I'm very new to this so please bare with me.

My 10 year old son has (high end) asd. He has several issues including fine and gross motor skills, sensory etc. 

I have been out of work to care for him and my other 2 children for some years now. I've recently started a college course. I attend twice a week from 5pm-9pm. I want to start work and absolutely love my course! However I'm having major issues leaving my son with a sitter whilst I'm out 

I'm a single parent with no involvement from their father and don't have a great support network around me. The children are cared for by a babysitter. She's brill and I cannot fault her in any way. We gradually introduced her to the family so it wasn't a great shock to the children. But my asd son is behaving uncontrollably while he's in her care! 

So my question is, without quitting college and continuing to be a stay at home parent, how can I entertain him while I'm away for the 4 hours? 

His attention span is practically non existent. He doesn't enjoy reading or crafts and gets bored of electro I've very easily! 

If anyone has any advice please share as I'm at my wits end and really don't want to give up college! 

Xxx