You could consider Speech Link and Language Link assessment and intervention packages, these can be run by TAs and other school staff.
Speech Link is for speech sounds for children 4-8 years old.
Language Link: there are separate packages for Infant, Junior and Secondary aged students (Up to Year 9).
The intervention packages contain all the resources you need to run the interventions and can flag up students who would benefit from a more specialist level of support from a speech and language therapist.
Here is some additional information: https://speechandlanguage.info/