B.E.

As such you are not required to learn any Course before joining engineering you start to clear exams. But I would recommend you to take some courses on the skills that will be requiring in your engineering if you doing engineering in Computer Science something it that then I believe if it is related to computers then I will I believe that learning languages like Python or SQL can help you also try to get acquainted with MS Office because it is very helpful in whatever Institute you go are in whatever feel you go otherwise you can also try out Some other courses from your area of interest like if you like to do something related to dance song for drama in Hindi like that try to do that it will build your extra curricular side which is important when you go in the institute and the Explorer as much as you can and studies are important but then I believe that should also try out things which you would like to do in this summer holidays are the go for institute and enjoy all the best.

Yes, you can definitely apply for it. To secure admission in PG programs, the candidate should hold any Bachelors degree of minimum 3 years duration from a recognised University. Also, candidates belonging to General category should have obtained a minimum of 50% marks in graduation and candidates belonging to reserved categories must have scored a minimum of 45% marks in graduation.
Note: Aspirants are advised to thoroughly go through the eligibility criteria as mentioned by IGNOU for the course in which they wish to secure admission.
IGNOU grants admission to its courses through three methods. The methods being:
-Direct admission for candidates fulfilling the minimum eligibility criteria
-Admission on the basis of merit
-Admission through Entrance Test
-Admission to majority of the courses is granted on the basis of merit.
Admission to a few courses is based on entrance exams that have different durations this majorly depends on the course for which the aspirant has applied. Admission to Master of Business Administration is granted on the basis of the scored obtained in the entrance test, OPENMAT. The exam is held twice in a year. Exception being MBA (Banking & Finance) where admission is granted on the basis of merit. Admission to Bachelor of Science and Master of Science in Hospitality & Travel will be granted on the basis of the scores obtained in NCHM JEE. The entrance test is conducted by NCHMCT. Admission to B.Sc. Nursing (Post Basic), Post Graduate Diploma in Clinical Cardiology, Diploma in Management, Master of Education, B.Ed M.Sc. Actuarial Science, M.Sc. Chemistry, M.Sc. Life Science, MFA Painting, MPA Hindustani Vocal Music is granted through an entrance test conducted by IGNOU.

BE computer science is more of an engineering domain and include subjects that study the hardware as well as software part of computer and allied devices. Hence, it includes some subjects on electronics engineering apart from the software subjects studied in IT. B.Sc. IT on the other hand involves the study of mainly the software portions. IT includes mainly the programming and applications based subjects and very basics of electronics. Regarding the scope, both courses offer wide opportunities in the IT field, but an Engineering degree holder will be better preferred as it is a professional course. Moreover, B.Tech - computer science/IT and MCA holders are treated on par in many scenarios.
All the best.