Let the royal babymoon commence! Pregnant Kate Middleton and Prince William have escaped the dreary weather in London for a holiday on the ultra-exclusive island of Mustique, a Middleton family source confirms to Us Weekly. Expecting their first child together, the Duchess, 31, and William, 30, are kicking back in a luxury villa with a $30,000-a-week price tag. The couple (who honeymooned in the Seychelles following their April 2011 nuptials) flew out to the island a few days ago to join Kate’s parents, Carole and Michael Middleton, the source adds.Some perks of the royal parents-to-be’s vacation villa? An infinity pool, games rooms and a private terrace. With Middleton completely recovered from the acute morning sickness that plagued the earliest days of her pregnancy, the twosome are ready to party -- with plans to hit Basil’s Bar on Wednesday (Feb. 6) for a "Jump Up” party.Middleton’s child is due in July.Us Weekly