Koru Kids is an agency providing students for after school care - not sure about mornings - they may not so mornings but being students would generally not expect holiday hours. (They are paid their legal holiday entitlement though, via the agency). Otherwise if you agree directly with a Nanny to work term time only you can include wording in the contract that they are only employed for work in term time, and that their holiday entitlement is to be taken by in school holidays.