How to email the heads of a department asking about whether they accept applications from undergraduates from a different discipline? I'm an electronics engineering sophomore at an Indian university, particularly interested in quantum computing, quantum information theory and quantum engineering. However, the problem I'm facing is that we do not have the possibility to take up extra theory courses in computer science (e.g. complexity theory, analysis of algorithms) or mathematics (topology, differential geometry, discrete mathematics, etc). I feel these theory courses are extremely important to understand quantum computing properly (more so, with stuff like topological quantum computing and relativistic quantum information, coming up). By the end of the 4 years of my undergraduate course while I'll likely be having sufficient background for further study in the area of quantum "engineering", I feel I'll be lacking in the theoretical aspects. For the record, I do have some experience with research in the area of quantum computing (I'm currently pursuing a undergraduate research project at a nearby university in my city). Also, I've been trying to learn some of the mathematics and computer science topics on my own, using various online resources.

For that reason I was thought if it would be possible for me to apply for a masters degree in computer science/mathematics, after my undergrad, before directly applying for a PhD in quantum computing. I feel that such a masters degree focused on the theory would make my PhD application stronger. A course like the one offered by Oxford: MSc in Mathematics and Foundations of Computer Science would probably be perfect for me (at least that's what it seems from a reading of the course contents). But, I'm a bit worried because the acceptance rate in such courses is already very low (for example Oxford has only 17 places available in this course while on average 115 people apply for it per year). 

So, in short my question is: Is it okay if I mail the head of the Math/Computer Science department head, asking whether they accept applications from electronics engineering students and what I can possibly do as an undergraduate, to improve my odds of getting accepted to such a course? (For example, the heads of activity of the Oxford's Quantum Group are listed here). Also, if yes, how should I frame my email? Suggestions are appreciated. Thank you.
There is nothing wrong with sending an email, but it should not be sent to the chair or head of the department. Instead, the relevant contact person is either:


the chair of the admissions committee, or
the head of the graduate studies program


Either of these officials in the department should be able to provide you with the requisite information. Sending it to the chair of the department is a waste of everybody's time.