Yes, Wideford those are the ones.
Moth & Jane if you can shed any light on alternative names id be most interested.
The site is on the D776 a mile or so NW out of Monteneuf towards Guer (which is about 40k SW of Rennes)
There is a visitors centre there (unstaffed at this time of year) and a reconstruction of a house and mock up of stone moving/lifting equipment. And LOTS of big stones.
Moth - I dont think thats it on the link you posted.
Must get around to posting some photos...
cx