Rubylady we have been through similar situations. Your dad probably does not have the capacity to make decisions, to use official terminology. It takes a while to establish this with all the agencies concerned.
I found my admiral nurse invaluable help, she stepped in for me, she supports you as the carer.
Your dad needs to have been in the forces, even national service counts, if he has do take advantage of this service. It's provided by the British Legion. The Alzheimer's Society can refer you, they have knowledge of everything available to you.
Take care and keep asking for support. 