You should speak to your child’s school if you think an assessment of needs should be carried out.
You can ask the school if they would support your request?
The local authority will contact the school or setting to request information on how your child was supported and to see if they have done everything they can to help your child.
You can request an EHC needs assessment by contacting the SEND Service at Enfield council.
You can also request re-assessment with the local authority if needs have changed significantly. Take a look at the information from IPSEA, including their template letter.