Stonehenge Inner Circle questions

We did the morning stone circle access in spring 2015 and no, there was no guide. Nor do you get an audio guide to wear & listen to -- this is included with the regular daytime entry fee, but it's not part of the morning/evening stone circle access. The closest thing to a guide is the driver of the shuttle bus taking you to the stones, who gives a short recitation of all the things you can't do: no touching the stones, no leaning against the stones, no laying coats or backpacks on the stones, no kissing the stones, ...

On our visit, a student group happened to be present and their professor spoke in her "outdoor voice" about the stones, sunrise/sunset alignment, archaeological finds etc., so we got to listen along with the students whether we liked it or not. That was simply the luck of the draw. We had already visited Stonehenge with regular entry tickets the preceding day so we had already listened to the audio guide, and this professor's comments duplicated some of what we had heard.

I don't believe there is luggage storage (you could ask if you call English Heritage before booking a stone circle access time slot), but the car park is fairly secure -- during the stone circle access hours, nobody can drive in without showing an entry ticket at the car park gate. Unless things have changed, you'll need a car because the Salisbury / Stonehenge / Old Sarum bus doesn't run during the early morning or evening hours. The restrooms are open but the visitor centre, gift shop, and cafeteria are closed.

If you are deeply fascinated by Stonehenge, as I've been since I was old enough to know there was such a place, the stone circle access experience is well worth it. However, I also recommend visiting during the regular daytime hours when you can listen to the audio guide, experience the visitor centre (indoors and out), choose to walk all or part of the way to or from the henge, browse in the gift shop and perhaps have a snack or lunch in the cafeteria.

There is a Stonehenge audio guide app, FYI. We haven’t visited yet so I don’t know if it’s good or not.

The Stonehenge audio guide app is pretty much the same as the guide that you get with your daytime ticket. It is good, and includes the numbered signs around the circle, information about the things that you can see outside of the circle, etc. Also, you can listen to the app ahead of time, or afterwards, in addition to listening while you are there.
The app that you would want is the English Heritage Trust one - a black background with a red "castle."