Dieting is tough for most people - that said once you get going it can be quite easy if you are clever.
3 takeaways removed a week with alcohol is probably around 3500 kcal over your normal intake (depending on the takeaway, fish & chips is a lot better than Indian typically for example) - that alone is 1lb a week weightloss if you're weight was level before. Add the exercise in and you're away!
The biggest thing for me was having a decent breakfast and then not getting hungry - in fact just doing that rather than a small one or just coffee seemed to kickstart my metabolism. 2 Weetabix (37.5g) is only 134 kcal - hardly enough for me to get me through the morning and I weigh less than you! I try to eat every 2-2.5 hours if I can, 5 meals a day is better than 3 with long gaps.
You could go the numerical route - calculate your BMR (basal metabolic rate) to see what calories you need to break even, then factor in excercise and give yourself a decent deficit. 3500 kcal for a 1lb of weightloss i.e. 1 lb a week = 3500 kcal deficit (500 kcal a day).
i.e. My BMR is about 2000 (+ ~500 for activity) = 2500 kcal to break even. I'm aiming to lose 1lb and a bit a week (i.e. 500-800 kcal/day deficit) so eat around 1800 kcal balanced diet with moderate excercise. I eat more when I do a long run (1hr+) burning nearer 1000 kcal. It goes up and down a bit depending on what we're eating in the house and what I like more - but averages out in a week. I use Myplate on livestrong.com to track it all as 99% of food I eat is in the database.
It's not an exact science, everyone is different (some need to eat a lot less to lose it, others can eat more) - but I'm a scientist and like to do things this way - keeps me motivated (I also track my weight v calories v excerise done and play with stats).
You can eat too little as well which makes your body want to store fat, so you get diminishing returns - a lot of people fall into that trap.
Edited: 04/01/2013 at 15:23