Is eating less with regular exercise enough to lose weight?

After a long winter ive decided to lose the belly but I have no idea about dieting and have never stuck to anything before. I partake in a fair amount of physical activity and lead a pretty active life. I play football for around 3-4 hours a week and visit the gym on average 2 to 3 times. Im a student at uni and my eating habits are bad. I eat a lot of fried food aswell as lots of fizzy drinks. I also drink alchohol around 2-3 nights a week. I binge eat alot and I rarely get my 5 a day. What I want to know is a simple plan so that with my exercise I can lose about a stone (14 pounds) in 2-3 months. Is replacing the junk with lets say 3 decent meals a day (e.g. cereal, pasta and something like fish for dinner), with fruit for snacks, diet cola and no more pints when I go out going to be sufficient. Or do i need to follow something a little more in depth with more exercise? Thanks in advance!