Hello Shiv!

You can get admission in any top university abroad after passing from NIOS. There is no bars if you are home schooled or passed out from an open school. But you to qualify exams like Toefl IBt ,IELTS ,SAT, GRE, GMAT with really good score to get admission into Oxford University, London. Assuming you are applying as an undergraduate, then it is the same process for everyone: via UCAS(Universities and Colleges Admissions Service).

You will have to submit the UCAS form, which will be about the information about where you want to apply, your previous education and examination results, as well as a 4,000 character personal statement. You may have to sit a test, depending on your subject. In case you qualify, you are called for an interview. This is hard for an international applicant.

The acceptance rate of Oxford University, London is about 18% and it is really tough to get into the software engineering course. As a result, you really have to score very good in english proficiency tests like Toefl and IELTS. As well as SAT(undergrad) and GRE(grad). This will ensure you many financial aids to get over expensive tuition and living conditions.

Go through this important links below(copy and paste in your browser):-

International qualifications:-

https://www.ox.ac.uk/admissions/undergraduate/applying-to-oxford/for-international-students/international-qualifications

Applying to Oxford:-

https://www.ox.ac.uk/admissions/undergraduate/applying-to-oxford

Hope this answer helps:)