Cruise control lowers your mpg. I very rarely use mine. You will get the best mpg by selecting gears manually and keeping a light right foot, and changing gear before 2k revs. Try to build speed gently, and try to anticipate the road and traffic ahead so you do not have to break hard. If you see traffic ahead, let off the accelerator and let the car roll along a bit.
From a 25 mile drive to work, 10 miles on motorway at 70-75mph, and the rest A roads at 50-55mph, I've had 86mpg out of my golf, although that's a BlueMotion. Generally I get around the 70mpg mark, and around 700-800 miles to a tank full.