India is served by a number of European, Asian and Gulf carriers from the UK, with flights arriving at Mumbai, Delhi, Chennai and Bangalore as well as the more popular tourist destinations such as Goa and Thiruvananthapuram.
If you're intending to see quite a bit of India in a limited time, a few flights are unavoidable as the road and train networks take simply too long to traverse a country of India's immense size. There are a number of Indian airlines and airports in all major cities. Flights are becoming ever cheaper. India's extensive rail network is an attractive, though slower way of seeing the country - just don't expect your train to be on time, ever! There are also a huge number of coach companies offering services across India. Many have air conditioning and sleeper facilities. Travel within cities is generally by rickshaw and taxi, make sure you agree on a price before setting off and as with everything in India, you'll have to haggle for the right price.
Bus and Train services are available to Bhutan, Nepal, Pakistan and Bangladesh.