Your best course of action is to contact Apple and ask for their help in sorting this out Tim.
This sort of question is a problem in the digital age. Companies are reluctant to supply information that can justifiably be considered confidential, even if the information belongs to the deceased. In any event if anyone can help it will be Apple. Since we are all just users like yourself, no one here will be able to help with account information.
Contact them here:
Navigate the options until you arrive at the ability to compose an email. It will be answered in a day or two, but be prepared for several more days of back-and-forth correspondence before you get the attention of someone who understands and can address your concerns.
Alas, that's where I went and found myself going nowhere until there was this forum was prompted to me, and even so this was not really what I was hoping to find.
In the digital age death does not seem to exist. This is so 'Brave New World'. Or is it grief is still screwing up my thinking?
I am feeling very raw as we had our Civil Partnership on 12th January, he died on th 19th and the 26th was his 57th birthday. Three Saturdays in a row of joy, pain and the knowledge he isn't going to be here any more.
I am sorry for your loss.
This story won't help you but it may be of interest to know what challenges exist and what is being done to address them:
... I don't remember now the route I took to get there!
It's a moving target, so providing step-by-step instructions may be frustrating anyway.