I live in the UK. You won't just be able to walk off the plane, there will be paperwork and i'd imagine it'll be detailed online or at least contact details so you can make enquiries.
First thing you might want to learn? The country is not called England. England is only one country of the UK.
OP, actually it seems you are ignorant of the situation. There is no sovereign nation state called England. The sovereign state is called the United Kingdom, and that's the country with a seat at the UN etc. Ok?
Secondly, England does not have its own immigration requirements. You enter the UK (as stated above). If you then choose to live in England that's up to you, and if you end up with citizenship you become a British citizen, not an English citizen.
And finally, as your own President displayed his ignorance by referring to the UK as England in a toast to our country during his recent state visit, it's clear that Americans ARE, in general, ignorant of the UK.