We've done Cunard with an 18 month old and are going again in the summer with our 2.5yo. Kids' club is available for 6months upwards but as vegasmum said, they have to have an adult with them at that age. Think it was up to 1 year on Cunard. So you'd basically have the baby with you all the time. No babysitting on Cunard ships but the kids' clubs are open till late (bean bags and DVDs. They all fall asleep, aww) but again this is only for older children.