It sounds fine for the most part when speaking, but if it is for writing, the style could be made more formal. -In English, sentences cannot start with coordinating conjunctions such as 'and', 'so', 'but', 'or' , and 'yet'. It is usually preferred to join them to the sentence which came before. -It is also strange/ not correct to place a comma(,) after them. -For 'but', you can also change it for 'however,' because it can start a sentence. -For the sentence that says, "... get something at the shop and eat that", you can make it more clear by saying 'to eat' to show the reason for getting the food. The way you said it makes sense, but it is better for speaking. -'during the weekends' is a bit strange. Maybe it is different in British English, but it seems more common to simply say 'on weekends'. If you want to make it more English in writing, you could write: I don`t really cook that often. I´m really busy during the week, so I always just get something at the shop to eat. However, I always cook on weekends because I really like making food. That´s what I do.

To me (as an American) this sounds really good! The only thing that sounds odd to me is "during the weekends" — a more native phrase would be "on the weekend." (For British English, you can say "at the weekend" instead.) If you want to use American English, I would also suggest using "store" instead of "shop." It's technically wrong to start a sentence with "so" but that sounds very natural/colloquial. The technically correct way to write it would be to connect it to the previous sentence: "I'm really busy during the week, so I always ..." Another way to write that sentence that sounds a little more native to me is this: "So I always just get something to eat from the shop."

yes, I think it is correct.