Department for Education (DfE)- School admission appeals
If your child is starting Reception in September 2020, you should receive an offer by email confirmation or letter soon.
The government has confirmed it will be making regulatory changes that, subject to legislations, will come into force on 24 April 2020. Once the documents are published, Portsmouth local authority will provide further details on how you can appeal if you are not happy with the school you have been offered.
Attached are some guidance from the government, Department of Education.