I'm trying to figure out the easiest way to grab a quick bite to eat between visiting the Vatican Museums and St. Peter's. We have a 10:30 Vatican tour reservation. We plan on taking the shortcut from the Sistine Chapel to St. Peter's but would like to grab something to eat before entereing St. Peter's and climbing the dome. Otherwise it could be quite some time between our breakfast and luch for our two daughteres who will be with us. Are there food vendors near St. Peter's square? Even if there are, I'm thinking that taking the shortcut to St. Peter's makes it difficult to take a sidetrip for lunch. Would we be better off carrying in some snacks and is this allowed?
We (with two kids) took the same tour last summer, and exited to St. Peter's from the Sistine Chapel. You actually don't come out into the church, but into a little open area by the entrance to the crypt. But you are inside the St. Peter's security, so it is helpful that you don't need to wait in the security line. We did eat a snack we had brought with us in the little area, before entering St. Peter's. I don't think there was a place to buy food there, but I wasn't really looking for that. In case you are interested in getting up early, we actually did St. Peter's and the dome climb before the 10:30 tour, which was nice because it was not crowded, and a little cooler for the climb. I think we got to St. Peter's between 8 and 8:30 AM. We went through the crypt and back in St. Peter's briefly after the Vatican Museum (and snack).
If you take the shortcut from the Chapel to St. Peter's, you do not have access to the Square, which is on the other side of the security line. The shortcut takes you to a "porch" right in front of the doors to the Church itself. If you want to visit St. Peter's and climb the dome without leaving and returning again (which involves another trip through the security line) your only option is to pack a snack. As long as you aren't eating in the Vatican or St. Peter's itself, I don't think anyone will mind.