Ms Willis, who has an eight-year-old son at the school, became embroiled in the row when she faced redundancy and asked if she could volunteer as a teaching assistant.
But she claims the head refused, telling her that her battles with postnatal depression "made her a high risk to young people."
Ms Willis then lodged a complaint with the school and asked to have her concerns heard by a panel of governors.
The school claims Ms Willis then "verbally" dropped her complaint, which she disputes.
She added: "About three-and-a-half years ago I had postnatal depression and in June this year I was being made redundant and went to the head teacher to ask about volunteering work.
"She said no, which was fine, but when I said about other schools she said teachers talk and because I had mental health issues I was a high risk to children. I felt this was a breach of data protection to discuss my personal information.
"I escalated it to the council who did an investigation. I apparently said I didn't want the complaint to continue, but that isn't true.
"I'm not happy with how the school or council is treating people who have postnatal depression and I want it to be stopped."
In a letter Rob Johnstone, from Stoke-on-Trent City Council, defended the school's action.
He claims Ms Willis met with the school business manager in June, adding: "At the conclusion of this meeting you advised the school business manager that you would not be pursuing the complaint as you felt it was not going to "get you anywhere".
"From the school's perspective, the complaint was therefore closed and there was no requirement for them to escalate to the third stage of the complaints procedure which is a governors' complaints panel. We have no evidence to suggest the school's recollection of events is incorrect.
"In this case, having reviewed the documentation, the decision to ban you from the premises was unrelated to the handling of your complaints. It was instead carried out in line with the Department for Education's guidance advice on school security."
Heron Cross Primary has been contacted for comment.