As to your goal to get more exercise:

I work at a computer for 9 hours a day, and spend about 3 hours commuting on a train

I wouldn't spend extra energy working out. When I commuted last summer 3 hours/day I found that working out wasn't worthwhile. I exercised like a maniac the first month and a half and then just lost all motivation. Maybe 30 minutes, 3 times per week, but in order to keep a healthy body, I would suggest improving your diet. This is just advice; take it or leave it, I'm not trying to tell you how to live your life.

1. No bleached white flour, no hydrogenated oils. No amount of these is acceptable in a healthy diet. Sources: any fast food. Most breaded/fried food at restaurants. Margarine (I think). Check the ingredients of anything you eat. Anything that says partially hydrogenated, or most white doughs you should avoid.
2. Minimize sugars and saturated fats. These aren't unacceptable in any amount, like bleached flour and hydrogenated oil. However, they should be kept to an absolute minimum (and you can actually really cut them out completely, it's not impossible). Sources: non-lean meats, desserts, candies, many many other things (check nutrition facts!). For every gram of saturated fat you consume, try to consume a few grams of polyunsaturated or monounsaturated fats. These are found in nuts and grains.
3. Check where your calories are coming from. If you're trying to lose weight, get around 40-50% of your calories from protein, 40-50% from carbs, and <20% from fats. If you're happy with where you are, 30-40% protein, 50-60% carbs, 10-20% fats. This will change depending on whether you're male or female, and whether you are prone to being overweight, and many other factors, such as your activity level, any health problems you may or may not have, etc. FYI, 4 calories/gram each of protein, carbs, 9 calories/gram of fat. Minimize the amount of simple carbs you consume (e.g., sugars, I even try to stay away from potatoes, but they aren't terrible) and maximize the amount of complex carbs you consume (grains and rice are great, bread made from good flour is a good source of grains)
4. Make sure any changes in your diet are sustainable. If you aren't able to make your diet completely healthy, only change it as much as you can stand to live with. Your diet should be a lifestyle, not a 3-6 month fad. If you change your diet for a year or more, you may find that being healthy is a motivating factor for you, and you may be encouraged to keep improving it.

Good luck, and if you can find it in you to work out as well, you're far more motivated than I am.

Edit: after reading the rest of your post, I see that you want to move closer to your job. I strongly suggest this, especially if you want to have a social life and work out. With 12 hours/day spent on your job, having both of those is going to be really tough. Also, I saw that improving your diet is important to you. I do suggest cutting down on cheese. When I did a calorie count for my diet I had to do this as well, and it really made me sad...but it's worth it, in the end. However, this depends on what else is in your diet. If you don't have many sources of fat in your diet other than cheese, you may be okay, but this is not likely, fat is everywhere.
remember, immediate gratification<good diet