It is likely that a full educational psychologist diagnostic assessment and report is what is required for the processing difficulties. The people you mention can be used to identify certain difficulties but not educational aspects. SFE are now using a set of list of tests that are required within an ed psych report. If one is missing they are requesting it be completed.
As an Irlen regional centre we do assess students based solely on Irlen syndrome only, so SFE should allow this. To say this is a condition that does not warrant a needs assessment is wrong. It is a recognised disability under equality law.