No, they would have used Stonehenge for its original purpose...an analog computer for calculating solstices and equinoxes.
I suppose in some jungle somewhere, a witch doctor is still trying to figure out what to do with a lost-and-found HP35. In like manner, modern primitives are having the same problems with REALLY old models on non-solstices.
Worked fairly well!
Did you realize the inner circle of holes of the "analog computer" works out as a counter for the number of years between eclipses? We don't know what they really did, but if a stone is moved from hole to hole, the "count" for the number of holes gives the time to the next eclipse.
Means you need somebody to move stones "religiously" to keep the count up - since it's a long cycle, but that just shows it would be a stable culture whose priest class predicts what they'll need the 17 years, the next 17 after that, etc.
Pagans just aren't what they used to be....