Well I think its all to do with how willing you are to lose these pounds. You have to eat right (meaning not starve yourself) whilst exercising properly. If you're not much of a motivated person (like me :P) then you could attend a cheap gym and have someone help you set you something. I go to a thai boxing gym for 50 dollars a month for 8 lessons. Its pretty cheap here and its helped me lose a bit of weight, strengthen my abs, got rid of my arm and leg flab.
I'm not sure losing 8kg is healthy or not. Maybe you should aim to lose 1 kg at first and gradually see how well you do over the weeks. Losing 8 kg in a month will probably be a lot of stress on your heart?