The chances of an ordinary U.K Trades / Craftsperson getting employment in the U.S are as close to ZERO as you could possibly get.
The over-riding rule is, "Can a U.S employer find a U.S Citizen for the job"
In the case of trades or ordinary jobs the answer is yes they can.
There are exceptions if the skills required for the job are very specific and in short supply as in the case of my Son who is living and working there.
He only got a Visa as he was a Manager / Executive in the U.K for a company who also have offices in the U.S so in effect he was transfering.
But it still wasn't easy, his employer had to provide hard evidence that they had tried to find a U.S Citizen to do the job, which they did have as they had been looking for 2 years.
Visas are tied to the employer, loose your job and you have to leave the Country and re apply for a new Visa for a different job.
Visa's have a maximium limited time, 5 to 7 years I believe and unless you apply for a Green Card (Permanent Resident Card) you have to get out the Country when the Visa expires.
You then need to have been a Green Card holder for a certain time before you can apply for Citizenship.
My Son has had a Green Card application in for well over 2 years, being paid for by his employer at a cost including legal fees of around $20000.