What is banding?
Banding is a way for Local Authorities (LA) to allocate levels of top-up funding for securing special educational provision (SEP) for those children and young people with EHCP. These are not statutory arrangements and each LA will have its own mechanism for allocating funding.
Surrey cannot specify banding in an EHCP as this would be unlawful.
Banding and special educational provision (SEP)
Under Section 42 Children and Families Act 2014, the LA must secure all the special educational provision (SEP) in the EHCP. Therefore, Surrey should make sure that the funding allocated to an EHCP is sufficient to do so. Surrey remains ultimately responsible for making the provision if school cannot or will not do so. Banding should be allocated once the SEP has been determined and not the other way around.
If Surrey fails to secure the provision in the plan, then this would be a breach of its duty and you can complain and ask the LA to secure the provision. We have a model letter you can adapt for this purpose.
Banding and specification in the EHCP
An EHCP can refer to bands or other funding arrangements but not instead of specification of SEP (which, in most cases, will require the quantification of such provision see: SEN and Disability Code of Practice 2015; L v Clarke and Somerset  ELR 129; JD v South Tyneside  UKUT 9 (AAC); B-M and B-M v Oxfordshire CC  UKUT 35 (AAC)).
At the point where an EHCP is issued or the LA makes a decision following an annual review, if the EHCP does not specify the special educational needs (SEN) or provision then there is a right of appeal to the SEND Tribunal which you could seek specification.
Once the EHCP is in place, Surrey must maintain it. If the EHCP does not specify the SEN or SEP then you might want to see if you can have changes made to the plan, an annual review is a good way to do this.
Remember: Banding should never be a barrier to the SEP which is required by a child or young person being specified, quantified or delivered.