I enjoyed to be able to see these rocks in person, although they no longer allow you to go up to the rocks.
Admission is free if you have an English Heritage membership.
I highly recommend that you plan on seeing something else in the area such as Bath as they are only an hour away from one another. Allow about 30 minutes to an hour at this location.
Address: Off A344 Road, Amesbury, Wiltshire - SP4 7DE