Is it lawfull for office staff not to wear safety boots on the work shop floor?

Whether it is acceptable for office staff not to wear safety boots on the shop floor depends on the nature of the activities in the particular shop. If there is a hazard to feet that can be reduced by wearing safety boots or safety shoes in the places in the shop where office staff would go, then they should be required to wear them. If not, not. It comes down not to law but to good management.