Richard
we stayed for a couple of nights last year in the summer.
From what I remember, you go through the outskirts of Plymouth in a residential area, then down a quite narrow, almost single-track road to get there, but it was just about worth it.
The site was quiet, probably as there's no facilities except water and electric. I think it was all grass and it was quite steeply sloping, although folks had awnings up.
Lovely view across The Sound and nice walsks nearby.
Hope this helps.
Regards
Ken