It was very popular to simmer the gammon for the cooking time, which you may prefer to do if the meat doesn't have skin. Place the meat in a saucepan with enough water to cover and bring to a simmer then cook for the recommended time as if roasting. Keep the water topped up periodically, so that the meat is not exposed. Alternatively, remove the meat 30 minutes before the end of cooking and roast in the oven as a honey roast ham. You can also simmer the meat for half the time and roast for half if you prefer.