Childcare voucher doubts

Dear All

I am new to Child care vouchers. I am working for a small organization and I am higher tax payer. My wife will start her new work next month and she will be a basic tax payer. Both of our company never provided child care vouchers so far to their employees.

WE will send our 3 years old child to nursery soon.

I have 2 questions to ask.

1. Who should be requesting employer for child care for more savings? (basic tax payer or higher tax payer(40%))?

2. What should we do to request our employer to join child care vouchers?

Please guide me based on your experience.

Thanks