Will my subjects be okay for universities?

I have currently finished year 11 and residing in the summer break and I have applied to several schools in my area including 2 grammar schools and I am planning to do a computer science undergraduate course, in one of those grammar schools computer science is not a subject so I selected Maths, Mathematical studies, Economics and in the other school CS is there so I selected CS, Mathematics and Economics (FM is also there in that school but i chose Economics assuming that it would benifit my general life and as Maths is not my Strongest point yet I am confident at it). So i wanna know if CS,Maths and ECONOMICS would be okay for me to get into Oxbridge and other russel groups If I would attain the maximim grades three subjects.
Thankss

I have currently finished year 11 and residing in the summer break and I have applied to several schools in my area including 2 grammar schools and I am planning to do a computer science undergraduate course, in one of those grammar schools computer science is not a subject so I selected Maths, Mathematical studies, Economics and in the other school CS is there so I selected CS, Mathematics and Economics (FM is also there in that school but i chose Economics assuming that it would benifit my general life and as Maths is not my Strongest point yet I am confident at it). So i wanna know if CS,Maths and ECONOMICS would be okay for me to get into Oxbridge and other russel groups If I would attain the maximim grades three subjects.
Thankss

What is "mathematical studies"? Is this an A-level separate to A-level Maths? Note universities normally expect applicants to be doing 3 A-level subjects or equivalent.

Assuming the subject you are applying for doesn't have any other required subjects there's no issue with the combination of maths/CS/economics. Note though most "top" universities for a degree on CS prefer to see A-level Further Maths if available, and likewise for economics at degree level. If Maths is not a strong point for you though then those degrees are probably unsuitable choices for you anyway.

Some Russell Group universities (e.g. Cambridge) like to see Further Maths in addition to Mathematics. For example, the Entry Requirements section of their Computer Science page, here, says:

"All Colleges require: A Level/IB Higher Level Mathematics*
Some Colleges require: A Level/IB Higher Level in at least one other science/mathematics subject
Further guidance: A Level Further Mathematics is very strongly encouraged. If unavailable or you’ve recognised its desirability too late, we’d advise you to do as much additional pure maths and decision maths as possible, eg by studying Further Mathematics AS Level, or by using online resources covering advanced material. Good performance in maths competitions can be a positive aspect of an application."

BTW, if "Mathematical studies" is this qualification from AQA then (a) it's not an A level and (b) there may be too much overlap with Mathematics for your application to be competitive.

I suggest to pick some universities to which you would be interested in applying and check their entry requirements for Computer Science. Also, if they use phases like "other science/mathematics subject" (as Cambridge does) check whether that would include Economics or Computer Science.

You can check if your subjects are suitable for your desired degree by looking at the pre-requisite subjects in the entry requirements on university websites. The preferred/facilitating subjects list top universities used to produce has not existed for a long time.

Your ability to get into competitive top universities or competitive courses is not decided by your subject choices (providing you cover the pre-requisites) they will look at your academic potential & track record via the application process.

*Russell Group

Thank you for your response, I checked my desired universities' websites which mentions Maths and CS to be essential which is why I wanted to know if Maths/CS/Econ would be a okay for me to do a CS degree at the best ones

Thank you very much for your response, Mathematical studies was mentioned as a seperate A level but I frankly did not pay much attention to that school and the other school is my main target since it has all the subjects required for the course. It is specifically cybersecurity that I want to do but the best universites do not have a specific course for cybersecurtiy and for that I contacted one of my families friends who is a teacher at Oxford and said that cybersecurity is done at a college in Oxford. I just wanted to clarify whether Economics would make me eligible to get into a good university

Thank you very much for your response, Mathematical studies was mentioned as a seperate A level but I frankly did not pay much attention to that school and the other school is my main target since it has all the subjects required for the course. It is specifically cybersecurity that I want to do but the best universites do not have a specific course for cybersecurtiy and for that I contacted one of my families friends who is a teacher at Oxford and said that cybersecurity is done at a college in Oxford. I just wanted to clarify whether Economics would make me eligible to get into a good university