flyttande

Hello all.
It is the first time I've written here. I apologize for writing in English.
I want to move to Gothenberg and prefer to live in a big house as it is easier for my disabled son.
I currently live in Nyköping and have four children aged 20. 17. 10. 6 years.
The main reason for the moving is the lack of a children's hospital in Nyköping, which leads me to travel several times a year and for a long time in order to care for my disabled child.
I need to know the transition steps and enroll my children in schools that suit them.
I need help renting a big house, I have a job and a very good income.
Can I move at any time of year, or does the school accept students only at the beginning of the school year?
Thank you and appreciate the clear and detailed answer.