Op, i was in same boat as you about 4 yrs ago. I had successful career but no sch or SIMS experience. I did an online SIMS course and added it to my CV.
After 15 failed sch job interviews i finally got a job! A sch took a gamble on me , based on my corporate history but mainly my personality and my raising of my children, my involvement with their schs , the childcare i have provided to others in the community and my commitment to young people in the community and wanting to contribute something back. All substantiated by written references.
I have flourished there since and i love working with and supporting children and families.
Keep going OP but maybe do an on line SIMS course. Sometimes securing jobs is not about what you know but who you are.
What can you bring to the school and the children? Are you applying to make a contribution to children or are you applying for term time work to serve yourself? What examples of serving children in your community can you provide?
What documented contribution have you made to children and families in your community? Have you been active on PTA in your own DC's sch? Have you volunteered for sch trips and been list99 cleared? These are the kind of scenarios that show schools that a person has a proven long history of contributing to children and families and not in it for for holidays.
Children and families can be complex, You need to apply for roles like this with a greater view to contribute.
This is not a job to apply/take , to cover your child's sch holidays.
This is a real and proper role. Sch's will always need to see a genuine commitment to children and families, even in admin roles.
Admin roles will often be the first line of defence in safeguarding.
Admin roles are appointed very carefully. You do not need to know SIMs but you do need
to understand children and families and you need to demonstrate a long term and proven history to children and families and what you can offer to make these children's lives more secure in terms of education.
Did you supply any sch attendance initiatives for example?
You cannot just work in a sch because it suits your childcare requirements.
You work in a sch because you have something to offer and benefit young people
and children and families. You will have proven contribution to your community and DC's sch if appropriate.
Being a genius admin whiz is not sufficient to secure a school role.