You and almost every other American on Yahoo.
To get a visa for the UK, you need the qualifications and years of experience to successfully apply for a job on the occupation shortage list (mostly medical / technical). The employer, having proved they can't find an EU or UK to do the job then sponsors your visa.
If you want to study in the UK, you can do so as long as you can gain a place at a UK university and afford the costs - you'll need to prove you've got the funds (at least ￡10,000 living costs a year in lOndon, plus fees start at around ￡15,000 a year). Student visas are valid only while studying; you can't stay and work afterwards.
If you are a U.S. citizen, you can't just move there. You would have to work for an international company that transferred you there or have some special skill so that a U.K. company would hire you and get you a legal work visa.
There are 3 month work visas for students who have been enrolled in a college or university the preceding year. You can get a job waiting tables in one of the tourist areas.
London is very expensive so hopefully you have a high paying job lined up before you move there.
If you are an EU citizen then go right ahead. If not, forget it.
