Visited this in August this year and did not have any access problems.
Reading the previous post and Burl’s notes, it sounds as if both tried to access the circle from the footpath running past How Farm.
I took the road to Seascale Hall and parked at the gate where the footpath from the W joins it (roughly NY040027). Following the footpath under the road and along Newmill Beck both avoids any fences and, until the last minute, views of Sellafield.