Also be aware the UK is going through some tough times at the moment plus unless you have a EU passport or experience in the shortage occupation list you may find it hard to find a employer and work permit
I'm planning to take a PG course in Nursing Mgt. in UK. After I take that program, would that make me eligible to apply under the ONP of NMC? After finishing my studies, I'm planning to apply for the Tier 1 Post Study Work Visa which is valid for 2 years. Would that make things easier for me to be employed there?
Once you have your license you can apply to the NMC but they do request 12 months nursing experience so coming over to the UK and not work as a nurse may go against you. I doubt anything will make it easier to stay and work after the 2 years as the government has stated several times lately that they are going to make it harder if not from the EU to stay and work. Job requirements are already that unless on nursing short occupation list that the job is offered first to UK citizen then EU before the rest of the world. If you look back at Sharrie's posts, she deals with recruitment in her area at her hospital, if not from UK/EU then generally your application doesn't make it through the first round and reach the nursing managers
Immigration to many countries is rough at the moment and hard for the government to justify approving work permits if hospitals are closing and UKC are struggling to find work in the same way many other countries are doing the same