Would it be more effective to lose overall body weight if I went walking briskly for 1 hour a day or dance around my bedroom for 1 hour? I'm trying to save money, hence not going to a gym.

'Dancing at home to lose weight' is an idea I've never considered. Professional dancers are usually trim, taunt and terrific so I guess prolonged dancing could be a pleasant way of burning calories....but....the dancing would need to be fairly vigorous and the style of dancing would need to involve most parts of the body.

Power walking is probably your better option. There is a technique to power walking, it is not just a casual stroll around the neighbourhood. You need to work your upper body whilst you drive your legs forward. When the walking becomes comfortable, find a track that has a few slopes/hills and attempt to maintain a steady pace throughout the walk.

As your fitness improves and your shape/body weight reduces, you might like to consider other exercises that can be done outdoors without the need for a gym.

day time walking might be overheating you and be uncomfortable, so a lots of water to drink. Nightime it can be dangerous, especially for the foreigner.

if you live in the city I would rather dance with an aircon on, rather than inhale all the traffic fumes

Briskly walking, at least for me, does not get me breathing hard enough. You need an exercise which will do 2 things: 1) Increase your heart rate to over 150 bpm and 2) Keep you breathing volumous amounts of air. As a general rule of thumb, if you can carry on a conversation as you exercise, you are not breathing hard enough and you are, therefore, not acheiving item number 2.

You should also be sure to do this for 30-45 minutes per day, 5-7 times per week. Anything less than 20 minutes will not have begun to breakdown fat as you are using stored energy in your muscles for the first 20 minutes of the exercise.

Also, do not skip meals. Keep eating, but just cut back on sugars and startches in your diet. Stick with veggies, fruits, nuts, dairy, whole grains and meat. Cut back on alcohol (especially after exercise). Skipping meals and going malnourished for more than 48 hours can and will cause your body to store fat. Keep eating small amounts of food every 3 hours. Of course, you already know that you should be drinking plenty of water throughout the day.

Good exercises to try will include shadow boxing/kick boxing, plyometric exercises, a even dancing. There are plenty of cheap aerobic videos out in the Thai market with different things you can do. Be aware that some of these exercises are high-impact and can create joint difficulties over time.

Finally, strength train. Build some muscle, if even a little. Muscle burns calories and looks good too.