Re: UK/London
London is a big city, there's a lot more to it than the few square miles of tourist attractions in the middle.
What work did you want to do?
There are vacancies for all sorts of things, but in my experience (IT; I'm a weekend warrior when it comes to audio), competition is fierce.
You need qualifications. To be precise, you need better ones than the other 50 or so applicants that are also going for the same job as you.
Language skills are good to have as well. If you can speak one or more additional languages to English, that should put you in good stead.
It should also help you when paying for gas or shopping in a 7/11!
Shops and stores are always on the look out for staff, but it's generally unskilled work and therefore won't pay all that well.
Unless you have a track record as a manager at JC Penney or Macys, etc, you probably won't be able to enter at management level.
Restaurants always need waiting staff, but pay may be an issue. A 10% tip is the norm in the UK.
This is why we're thought of as tight when we visit the USA. The flipside is that we think Americans are generous when they leave a 20% tip over here...
As with the rest of the world, there is a recession on. I haven't had a pay rise (not even cost of living) for nearly 5 years now, yet gas, food, etc keeps getting more expensive. That's a general thing, not just London.
Without any more info on what it is you'd like to do for a living when you come over, it's hard to point you in any direction.
Sorry if that's not what you want to hear.
The grass in London is green, but I doubt it's any greener than anywhere else at the moment.
And there's more to the UK than London. Lots more.
HTH.
Karl.