London...NEVER DRIVE THERE!! It's a nightmare
I live in Milton Keynes, a city an hour north of London. And have only been there about 5 times my whole life so honestly cant tell you much.
Do the usual stuff, see the sights like Big Ben, Millennium Eye etc - I'm sure you'll check them out.
"Oxford Street" and "Knightsbridge" have really high end shops if you fancy window shopping.
Depending on what you're into, there is countless historical shit to look at - London Bridge, British Museum, Tate Gallery to name a few.
Or on the other end of the spectrum if you want to see a massive traditional British market, check out "Borough Market"
The tube (subway) is the best way to get around, I would take a little map of the set-up with you though as there can often be closures on stops where maintenance work is being carried out.
Also..."mate"....Everyone will call you it whether you know them or not! So just go with it.