I haven't ploughed thru all 6 pages but wanted to say you'll be fine. Here are some useful tips.
Have a handbag you can put the strap diagonally across your body. Have the flap/opening facing you.
Carry your travelcard (you can buy an oyster card online) in a place where you can reach in and get it instantly.
When you get on a tube try to stay near the door so you don't get trapped half way down the carriage. It is normal to travel extremely near (touching) to the next person.
When you get off move over to the wall. Don't stop as you get off cos people behind you will shove u out of the way and tut. Once by the wall look up for signs to tell u where to go.
On escalators standd on the right. If you are on the left then walk up. Walk off without stopping - again walk to a wall if u want to get your bearings and look up for signs.
If you are on the pavement and you hear ambulance or police sirens then move away from the kerbside.
There's lots of one way roads. Whenat a crossing look down first cos they will tell you which way traffic is coming from. Drivers are fast in London and shoot out of nowhere.
I was there for 13 years never once mugged etc. It's an amazing place. Budget for taxis if u feel nervous but think of a few places you want to see and go do it. Take a book/kindle and even if you quake walk in a restaurant for food. Noone will bat an eyelid. Take lovely bubble bath to relax after a long day. Travel in flat shoes and change on arrival.
Don't forget to tip in restaurants and to say "round it up to x" when you ask your taxi driver for a receipt butbefore you pay.
Constantly look up and gawp at the buildings - it's amazing. Throw yourself at it. Business trips "abroad" are scary so ignore all the critics on here.
Have a wonderful time.