Hello Carole
I did not use machines myself but I think it would be pretty easy, as we were allowed out on the streets on our own quite often (unlike my first trip to India). I normally take most of my money in cash as I have had experiences of cards not working or being blocked in third world countries, but I think India is relatively advanced in this type of thing. Prices were generally cheap and I did not spend much.
On the outward trip the flight from Mumbai to Cochin was on the “low fair” part of Jet Airways, so all food and drink had to be paid for in rupees. The problem with this is that you can only get rupees in India so you need to either try and take some water through security at Mumbai or try and change some money at Mumbai. You will not have much time due to it being your point of entry and you also need to catch a bus to the domestic terminal. This does not apply to the return internal flight as we were served a full meal.
Ideally you need an Indian, three round pin adaptor. These can be bought off eBay for £3. I have never seen them in the shops in the UK
Some of the women had clothes made at a shop just outside the last hotel. They took a garment in and it was copied.
If you wish to make phone calls to the UK I recommend you take an unlocked phone and buy a sim card in India. I paid about 1250 rupees for a card with 1000 rupees of credit. This gave about 140 minutes of calls to the UK. If I had used my UK sim it would have been £1.99/minute. To buy a sim you need a copy of your passport and visa (colour), a passport size photo and something from your hotel, I used a currency exchange receipt.
I can’t think of anything else to tell you but again feel free to ask questions.
David