Thank you so much for your input in advance!
It depends, really.
For accommodation - what's your budget? Accommodation in London is very expensive, and you can easily spend £100 per night in a 'cheap' hotel. Elephant and Castle isn't a lovely area, but it is well connected.
For things to see and do - what are you interested? London has enough galleries, museums, plays, gigs, shops, parks and lots more to keep you busy for months, so I wouldn't worry about running out. Buy a guide book, or take a look on the TimeOut website.
For transport, get an Oyster card (you can order in advance from the TFL website). Its the cheapest option, and covers tube, bus, and overground journeys.
When I was a child I had one set of Grandparents in London and another set near London so that year after year when visiting my grandparents I went to London many times and never ran out of places to go. The tube and the bus dont take cash anymore and you have to buy an electronic ticket in advance. I like the South Kensington museums (free the last time I went) and the maritime musem and observatory at Greenwich. The theatre is very good but not cheap. Dont forget theres more to Britain than London. Brighton is interesting. If you arrive at Gatwick airport Brighton is only about half an hour South on the train in the opposite direction to London.
You will not run out of things to do. Many of the attractions take half a day to see. Some could take a whole day. My cousins from Canada spent two weeks in London and loved every minute of it. They couldn't see everything in the two weeks and will be coming back again and again for more!
There are countless guides to help you find things to see. One of my favourites is The Natural History Museum. It's housed in an amazing terracotta building.
If you visit the West End Theatre, buy your tickets from the Half Price Ticket Booth in Leicester Square and save a fortune.
I wouldn't choose Elephant & Castle. I's a bit grim there. West London would be nicer.
You can buy an Oyster Card to travel around on the tube etc.
As has been said by alan P. There is more to UK than London. You can easily travel out and see England. eg. You could take a train to Portsmouth and cross by ferry to the Isle of Wight and find a whole different pace of life. Or travel to the Brockenhurst in The New Forest, William the Conquerer's hunting forest. There are bus tours out to Windsor and Stonehenge
I lived in London for 25 years - have yet to see many of the museums. You won't have time to see much of London in 7 days ; as a tourist you would need weeks if not months - you could spend all of one day in one of the larger museums.
I don't recommend the Elephant & Castle area alone at night unless you are street savvy - it has not got a very good reputation.
I have visited 8 times and Still have not seen everything!
It took me 2 visits just to see all of the V& A Museum and I have only done 1 floor of the British Museum
Go to the bookstore or library and get some London Travel Guide books and start Reading them
There are over 100 museums in London- Theater/Music/Art /Gardens/ Historical site/ Shopping/ places to see
http://www.londonforfree.net/
http://www.freelondonevents.co.uk/
http://www.walks.com/
http://www.timeout.com/london
7 days isn't near enough time in London. If you think you'll run out of things to do I suggest you buy a guide book.
If you think 7 days will be to long your never been to London
London is full of music venues, theatres, monuments, parks, open spaces, bars and nightclubs. Just look at the listings here:- www.timeout.com/london
These links will help you see more of London than just the main tourist sites.
London Secrets
http://www.thrillist.com/entertainment/l...
https://www.youtube.com/watch?v=m068KWpD...
Welcome to London, your city.
From the moment you set foot here in London, you are a Londoner
Londoner since 1941
AVOID The Elephant & Castle like the plague......