I want to introduce cuneform, or rather writing on/of clay tablets, is there any specific mention of particular writing stuff in TES?

They write with quill and ink and occasionally charcoal.

Ysgramor invented a system of writing I now believe to be based off the script and speech of Atmora, which is the script and speech of the dragons, before the Nords were recognizeably Nord, making them possibly the most literate early human culture.

Imperials definitely use quills and ink on parchment or paper, as do Dunmer, by the 3rd era.

Scrolls are written on, but bound books are often used.

That being said, there is also numerous proud oral traditions in several cultures