You must have your own interest factors when applying for a double degree, otherwise it will be difficult to stick to it in the end. I studied finance in Wuhan University for two years, but I saw the team getting thinner and thinner. There are not many who can stick to it wholeheartedly until the end.
About preparing and studying finance, you must have a good knowledge of mathematics and English. Finance needs strong mathematical model analysis ability and statistical measurement ability. In addition, studying for a double degree is a very demanding thing. Studying a double degree means the loss of your free time on weekends, so good living habits are also a big requirement. If you really have a heart, you should standardize your life rules from now on, be less impetuous and stay up late less. This is really important, which is the main reason why most people can't make it to the end. People are easily influenced by the environment, but since they have chosen to persist, they must keep their pursuit. Personally, I think the content of the double degree in finance is wonderful!
As for your own education, your major is computer science, which is very suitable for a double degree in finance. I am also a computer major. Personally, I feel that the advantages of mathematics and computers in learning finance are still obvious, which can be regarded as applying what they have learned.
Finally, I emphasize that interest is really important. I hope my answer is helpful to you. If you are interested, you can continue to communicate. Have fun!