Will I Lose Weight This Way?

Hi everyone. I'm currently at uni, have put on a significant number of pounds and would like to lose weight. I have signed up for the gym and was wondering if I did 25 minutes of cardio 5 days a week combined with light weight work, will I lose weight? Typical food for the day would be speacial k/all bran for breakfast, lunch a salad or sandwich dinner brown rice, some kind of meat/fish and veg....fruit for snacks....plenty of water/green tea through out the day. How long will it take for me to take results roughly? Thanks to all answers and for any additional advice!