The Indian currency is the Rupee. ATMs are available in most large towns and generally accept all major cards. It's worth carrying some traveller's cheques and cash as well. It's generally fairly easy to exchange pounds at a low rate of commission.
Whilst English is - along with Hindi - one of the official languages of India, the standards of spoken English in most of the country is fairly low outside the tourist trade and the business elites. This said, it is generally possible to make yourself understood as English is taught in schools and most Indians have at least a very rudimentary grasp of the language.
+91 for India
Travellers should be extremely vigilant in India. While violent crime is not particularly common, scams abound and pickpockets are very common. Women should not travel alone and even accompanied, should expect to draw a considerable amount of attention. Whilst most of this attention is just harmless curiosity, it can become unpleasant and overbearing. Be sure to check with a travel clinic before leaving to find out which vaccinations you need. Hepatitis A and B, Tetanus, Polio and Typhoid are the main vaccinations you'll need. Malaria is present in some low lying parts of the country - be sure to investigate before leaving and arrange the appropriate medication.