No. No, you cannot ring the doorbell. There is no doorbell. There are just massive, gold-tipped gates and a guard who looks at you like you just asked to borrow his crown. If you knock, the Queen’s equerry will not answer. Instead, a very polite police officer will ask you to move along. Don’t be that person.
Also, can you have a picnic on the front lawn? No, that’s sacred grass. But nearby St. James’s Park is perfect for a blanket-and-cucumber-sandwich situation. You can see the palace in the background and feel very sophisticated. Watch out for the squirrels. They’re aggressive.