Nobody in the Europe, where most Pprune members are, is going to be able to tell you which school to go to because you need to obtain DGCA ratings. You can't work outside India, so don't get ratings that aren't good there.
That said, I did a bit of research on JAA to DGCA conversion recently and the conversion is fairly simple, but it will cost you a bit. Going from memory, a JAA Integrated course would leave you about 30 hours short, while a JAA modular course would give you the minimum 250 hours needed for DGCA conversion. You would need to do a couple of extra cross country flights, as DGCA requires three of them, two of which are longer than required by JAA. You would have to get an Indian Medical, Radio license and take several DGCA Theoretical exams.
I would not recommend a JAA modular course because Indian airlines won't care at all whether you did a JAA modular or integrated course, so do the less expensive modular route if you decide to train in Europe.
Indian airlines can and do hire First Officers with just a CPL and no Instrument Rating, but having a JAA IR would probably make you more attractive to an Indian airline.
The least expensive route would probably be to take FAA ratings in the US then convert them to DGCA, but I have not researched what this would require, nor can I recommend a US school.
Some reputable modular schools in the UK are Atlantic Flight Training, Cabair, PTC in Bournemouth, Oxford Aviation Academy, Bristol and Exeter. There are dozens to choose from and other members may add to this list, as it is not exhaustive by any means and I have probably left off some good schools.