Kate Middleton is already nesting!

After spending their first year of marriage in a quaint Welsh cottage, Prince William** and his wife will make their permanent home in Apartment 1A of London's Kensington Palace, a four-story, 20-room flat undergoing a $1.5 million renovation.

"Kate is keen to put her stamp on the place with things she's bought on her travels," says an insider. "She felt certain pieces would be nice 'when we have a bigger home.'"

The couple, both 30, will move in there full-time this summer. A confidant told Us Weekly, "A baby is the main reason for the move."

The Duke and Duchess of Cambridge, who tied the knot on April 29, 2011, are eager to become parents as soon as possible. "They have been on such a high since getting married," a source close to Kate told Us. "It's time for the next step -- Kate is hoping she and William can become parents in 2013."

The confidant added about the move, "They want to bring a child up in a secure environment." The level of protection at their rented cottage on the sleepy island of Anglesey, even with all their trips to the movies and down to the shop, "just isn't enough," says the confidant.

Especially because the little one -- boy or girl -- will jump ahead of William's kid brother, Uncle Harry, in line for the throne. Last year, the United Kingdom made a historical constitutional change, giving a firstborn girl the right to succeed to the throne over her younger brother. (Queen Elizabeth II was crowned in 1953 only because she didn't have any brothers.)

This article originally appeared on Usmagazine.com: Kate Middleton, Prince William Prepare to Move to a More "Secure Environment" for Baby