Ian, check out the “Heavens above” website. If you enter your location it will tell you when the planets rise and set as well as opposition dates. You can also adjust the time and set it for when you hope to be observing and it will give you the altitude of the planet at that particular time – the higher the altitude the better the viewing. It gives the meridian transit time when the planet is at its highest point in the sky and which in theory is usually the best time for viewing. I'm a newbie and use it all the time.
http://www.heavens-above.com/