Most children with a Visual Impairement will need to be assessed for a Statement of Special Educational Needs (SEN).
Department of Education. SEN Toolkit. This looks at processes and the nitty gritty involved in getting the right Statement for your child.
IPSEA (Independent Parental Special Education Advice) is a National Charity for children with a disability, providing free legal advice.
The National Blind Childrens Society have advocates who are experienced in the educational processes of Visually Impaired children.
If you are concerned about your child's education, and don't feel you are being offered any help, it is your right to self refer to your county's Hearing and Vision Support Services. These teams should be sent your child's details when they receive a registration of Sight Impaired (Partially Sighted) or Severely Sight Impaired (Blind) and they should contact you and arrange an assessment of your child, your family, and what educational and developmental support your child may need. This team also should offer Orientation and Mobility Support (of the traditional kind, aimed at rehabilitation, as opposed 'No Limits Mobility'). It is also possible to self refer to a social-work team.