Hi Colin,
I’m surprised your having such a problem, especially as your not going to be a named driver.
My daughter is the person we claim DLA for and that paperwork is in my wife’s name but doesn’t drive. Therefore I am merely a named driver in our situation, yet only I have visited the dealership to place the order and collect. My wife signed the relevant document electronically via email. We completed the whole process over the last 3 months. I don’t know why you cannot do exactly the same thing.