Under the Early Years Foundation Stage Welfare Requirements there is a specific child to space ratio as below:

Under 2 years - 3.5 square metres per child

Two year olds - 2.5 square metres per child

Children aged 3-5 - 2.3 square metres per child

You cannot include storage areas, hallways, landings, cloakrooms, utility rooms, kitchens or bathrooms in this allowance.