Speech and Language UK is the children’s communication charity who have range of resources for practitioners and parents. You can use this tool to check whether your child has the key communication skills expected for their age. There is also an advice line where you can speak to a speech and language therapist.
The RADLD campaign was created to Raise Awareness of Developmental Language Disorder. On their YouTube channel, you will find videos that explain what a language impairment is, the impact it can have and how to get help.