She should look at the relevant information on the form. Last time I had mine done it had to be a professional person, i.e. doctor, policeman etc. who counter-signed. Being a manager of a nursery doesn't come into that category, I wouldn't think.
Managers of a VAT registered Charity, a VAT registered Company or a Limited Company are perfectly acceptable countersignatories according to the list produced by the IPS (Identity and Passport Service)...