While Kim has given the definition of Eternit, it must be pointed out that Eternit is the name of a company which gave the name to the type of fibre concrete sheet. I would without hesitation use Eternit here, and write it with a capital "E".

corrugated (asbestos) fibre cement cladding is the correct term in my opinion, as Eternit is just the brand name, but not the only producer UK or Europe wide.

Eternit also uses "fibre cement cladding panels" with no mention to Eternit at its own UK home page.
http://www.eternit.co.uk/Specifier/AboutEternit/1abouteterni...

The official EU eurodicautom translation is also "cement asbestos" for Eternit, so I think that the brand is a part but the function and danger - see below - are the more important part.

FAct-index.com says:...
Eternit is a brand of roofing and panelling material made of fibres and cement.
Originally the fibres were asbestos, and the material was commonly used in housebuilding because of its low cost, fire-resistance, light weight and other properties.

Now, after the discovery of its extremely high carcinogenic toxicity, its use is forbidden in many countries. Many ex-workers have sued the company and most scientists advise removing it from houses. Removal has to be done by specialized technicians.
<a href="http://www.fact-index.com/e/et/eternit.html" >fact-index.com</a>