Tried Google yet? Really, I don't think this is a unique question (and in fact there it is, on yahoo answers )

What I'd do (in addition to Googling and visiting sites like http://www.gpsinindia.com) is to visit the sites of the major GPS device vendors in the UK (Garmin, TomTom, ...) and see what maps they offer. The device will work as the sats are global. But without maps that's not too useful for many people (depending on your needs, of course).