Applying for a Certificat de nationalité française (CNF)

Hello I am hoping this is the correct sub, i will post to the askfrance one aswell if I can't find the answer i'm looking for here.

I am in the position of applying for my CNF (french proof of citizenship) as I was born in the UK to a french father. unfortunatly he has passed away so i can't have the ease of accessing documents without his nationality card.

I need to ask for the families birth certifcates, and this is a free service from the french govenment, but all the paths i go down to request them ask me for me idenity card, which i obviouly don't have. . . .

I've scoured posts and forums and everyone is pretty quick to offer the list of documents without going into detail about how to get them.

The question is, how do i request french documents whilst living in England and without a French form of idenity ?