Oxwich Bay Dog Walk: Information
There is a public footpath along the cliffs from Oxwich Bay Hotel, around Oxwich Point (shown in the picture above), and this path eventually leads to Port Eynon Bay. I have walked a few miles along here as an alternative to walking along the beach itself. It is a good walk with some wooded areas, a bit undulating/ hilly in places, then the path levels out with views over the sea. I have not walked as far as Port Eynon.
Apparently buses run every couple of hours between Oxwich and Port Eynon if you are inclined to do the full walk and then get a bus back, though I would not chance a return lift in winter as I doubt the buses are quite so frequent in the off season.