I regret that I may not be as familiar with UK laws governing the provision of services for students with learning problems as I am with US laws. I understand that there is considerable overlap - but you may wish to consult with folks locally as well.
With regard to dyslexia, I would hope and assume that, if actually diagnosed - the school is providing appropriate services to address your granddaughter's learning needs. Here in the US, students identified with learning problems receive an Individualized Education Plan (IEP) that is tailor-made to meet their learning needs. Some IEPs also allow for provision of counseling services in the event that emotional/behavioral issues are interfering with a child's ability to learn in school.
With regard to the panicky problems you discussed, I would be hesitant to jump to diagnosing any disorder. (Besides being inappropriate and unethical to diagnose over the internet and across the Atlantic, it may be too early to call her behavior "a disorder...") That is, your granddaughter may simply be experiencing some adjustment issues to changes in her school programming. This should be worked out among her parents and teachers (both regular education and special education). Parents always have the right to request a meeting to discuss these matters and this is no exception.
In the event that you feel that her behaviors have escalated to the realm of truly worthy of intervention, I would recommend that the family contact her pediatrician/family doctor for a referral to see a Licensed Mental Health Professional (LMHP) who specializes in both Child Psychology and Cognitive Behavior Therapy (CBT). See below.
PANIC DISORDER has been described as a catastrophic misinterpretation of mildly elevated physiological responses to the environment. It is considered one of the Anxiety Disorders and, as such, is felt to be related to applying the wrong response to a given situation. That is, fear is an adaptive function that all animals (human and otherwise) are born with... it is not learned, it is innate. When fear (the response) comes at the right situation (a hungry saber-toothed tiger standing in front of you), you're doing GREAT! Fear makes you move (fight or run for your life)! When fear (the response) comes at the wrong situation (at the grocery store or on an elevator, for example), you're not doing so great - and you need to relearn when/how to apply fear as originally intended.
Research has consistently demonstrated that treatment plus medication is more effective than medication alone or treatment alone for anxiety. Further research has shown that Cognitive Behavioral Therapy (CBT) is the most effective form of psychological treatment/intervention - particularly in dealing with anxiety disorders (like Panic Disorder).
A properly trained LMHP would be able to provide developmentally appropriate forms of CBT to address these fears and possible panics.
Thanks. I hope you're well and that this was helpful.
* FEEDBACK ENCOURAGED. Please contact me prior to leaving negative feedback so that we can resolve the matter. I am eager to work with all JA clients to provide them with useful/helpful answers. Thanks again.