Assuming that this is for a filming location or photo shoot for something else, then I think Dungeness is maybe a bit too familiar to other people. The landscape there is stunning rather than bleak, and some of the architecture down there is really interesting. Great as a place to visit, maybe not if you’re looking for a backdrop for an end-of-the-world vibe.
My suggestion would be one of the beaches on the north coast of Sheppey. One side of my family all come from there and so I know it pretty well. Anywhere from Minster to Leysdown to Eastchurch probably has what you want.