LONDON (Reuters) -Kate, Britain’s Princess of Wales, has undergone successful planned abdominal surgery and will be in hospital for up to two weeks, Kensington Palace said on Wednesday. Kate, 42, the wife of heir to the throne Prince William, was last seen in public on Christmas Day when the royal family made their annual visit to a church service near King Charles’ Sandringham home in eastern England, and there was no prior indication she was unwell. The palace statement said Kate was admitted to the London Clinic, a private hospital in the British capital, on Tuesday, and was expected to rem…