Sad to say,if you want to work in the USA you need a Green Card.
The USA enters all eligible overseas citizens into a "Green Card Lottery",unfortunately the UK is not part of this lottery process.
The only way to get a Green Card otherwise,is if a company in the US offers you a job.
However,due to the world financial recession President Obama has practically closed up that loophole.
So unless someone else on AB can suggest a (legal) way round it,then the answer is you won't be working in the US.
You can (legally) work anywhere in the EU,if that's any (small) comfort?