I do not think that Harry would live there with his wife. From the BRF site:

“Windsor Castle is an official residence of The Queen and the largest occupied castle in the world. A Royal home and fortress for over 900 years, the Castle remains a working palace today.

The Queen uses the Castle both as a private home, where she usually spends the weekend, and as a Royal residence at which she undertakes certain formal duties.

Every year The Queen takes up official residence in Windsor Castle for a month over Easter (March-April), known as Easter Court. During that time The Queen hosts occasional ‘dine and sleeps’ events for guests, including politicians and public figures.

The Queen is also in residence for a week in June, when she attends the service of the Order of the Garter and the Royal Ascot race meeting.

Windsor Castle is often used by The Queen to host State Visits from overseas monarchs and presidents. Foreign Heads of State enter the Castle in horse-drawn carriages through the George IV Gateway into the quadrangle in the Upper Ward, where a military guard of honour is drawn up.

Many Royal weddings have been celebrated in St George’s Chapel, most recently that of Prince Edward and Miss Sophie Rhys-Jones in June 1999. In 2005 a service of dedication and prayer was held in the Chapel following the marriage of The Prince of Wales and The Duchess of Cornwall.

Funerals such as those of Princess Margaret and Princess Alice, Duchess of Gloucester, have also taken place there. Queen Elizabeth The Queen Mother lies buried in the Chapel with her husband, King George VI, and Princess Margaret, her younger daughter.

Various departments of the Royal Household are based at Windsor Castle. The ancient Round Tower houses the Royal Archives and the Royal Photograph Collection.

The Print Room and Royal Library house precious drawings, prints, manuscripts and books in the Royal Collection. These are shown in a programme of changing exhibitions in the Castle’s Drawings Gallery.

Those who live and work within the Castle include the titular head of the Castle community, the Constable and Governor of Windsor Castle; the Dean of Windsor, Canons and other staff who run the College of St George; the Military Knights of Windsor; the Superintendent of Windsor Castle and his staff, who are responsible for day-to-day administration; the Housekeeper and her staff; and soldiers who mount a permanent military guard in the Castle.”