For IMU CET preparation, NCERT Class 11 and 12 books are the best. Read the NCERTs thoroughly. Along with this, you are also tested on General Knowledge and Current Affairs and Aptitude. You can practice aptitude online. Read newspapers daily for Current Affairs. For general knowledge follow some important topics like Ocean and Ocean currents, Countries and their Currencies, Their capitals, climate of different countries and water bodies etc. In this situation it is difficult to buy any books unless you can purchase it online. So you have prepare for the exam with what you have in your home also taking help from internet. If possible, you can practice Quantitative Aptitude by RS Aggarwal. Also try to solve previous year exam papers.