Leaving school help

My daughter, Chloe, is leaving school at the end of this school year. She will be 18 by then. She is looking round colleges with school, seeing if she would like to go to any. 

She would love to work with sen children, mainly with autism. 

My fears are transitioning her out of school ready for the summer holidays, which she already struggles with. 

How can I make leaving school easier for her? Does anyone have any tips?

Many thanks,

Lucy