I bought some Mars Celebration and Cadbury chocolates and toffees yesterday in my local store in Australia. I'll take them as gifts for my friends when I return to my country, Bangladesh, in 6 weeks.   How should I store them. Is it okay to leave them at room temperature? 
Your gifts can certainly be stored at room temperature, if the range is not much higher than 21-34 Celsius/70-75 Fahrenheit.  They won't be harmed by placing them in the frig, either.  However, you will want to take them in your carry on baggage, since end-of-year temperatures in Australia and Bangladesh can be quite warm. Should they become softened in transit, refrigerate them after you arrive. They might not look quite the same, but they're wrapped, and will firm up and taste the same. 