Yes. Cunard, P&O and Fred Olsen as part of World Cruises sail from Southampton to New Zealand. However, sailing only once per year usually starting off in January. You can leave the ship in New Zealand and many other destinations, and can also embark at different places. You should ask for a price for a cruise only voyage, no flights needed.
Take a round-the-world cruise and get off halfway. You have missed them all for this year. Saga Rose and Saga Ruby left today and QE2 and QV leave tomorro.