I want to do research in theoretical physics , so how much is the importance of good college or university( as compare to to imagination , creativity & Knowledge )
Expansion in vacuum does not produce work, says thermodynamics. If a good university is not available, try RG, publication, groups, etc. Try the Voevodsky route, see https://www.quantamagazine.org/visionary-mathematician-vladimir-voevodsky-dies-at-51-20171011/
The university only really matters in Grad school. Even then, good is what works for you. If you don't click with your adviser, it will be more difficult to develop the skills necessary for your work. Research the schools and your potential advisers. Make sure there are at least a couple people at each school that you could see yourself working with.