See BSc Computer Science means that you are specializing or doing an Hons course in Computer Science. This means, that the BSc Computer Science course is a more detailed course regarding the computer science and you learn in depth about this subject. But in case of BSc in CS+Physics+Mathematics, you will get the more than intermediate level of education in this three subjects. The topics will not be that much elaborative as in BSc Computer Science.

Now if you want to pursue a career in computer science, then you have to put extra effort and do course like Programming in Python, Java, SQL or Data Science courses, in order to make a more prominent CV which will help you to get a job.

For more information regarding computer science you can consider the link below:

https://www.careers360.com/courses/computer-science-course

I hope this helps.