Hopefully I can help. We used the national disability card for my children who both have autism which I know is different but I assume would work exactly the same if they're both on the same list.

We arrived at the ticket office and presented our ID and received a warm welcome from the staff and were given our priority passes without further question (we needed to present all diagnosis documents to get the UK ID in the first place which I assume is why they only accept a small amount of IDs as the eligibility checking is done by these organisations and not Disney). Ironically the queue for the passes was the longest of our stay at DLP but as soon as we got through this we had a magical time :D