Hi James, welcome to the forum.
One of our moderators will guide you through the process.
As your wife has dementia, I just wanted to check that you are claiming Attendance Allowance for her?
Did you know that she has also been EXEMPT from Council Tax since she developed the condition? It's easy to claim, the council send you a form for you to give details of the GP, who they then contact. This can be BACKDATED. The highest refund I've heard of was £8,000!