What is the process for an American student wanting to study in the UK?

Hi, I'm from California studying at a community college. My major is Political Science for transfer to a state university, where I plan to pursue a Bachelor's degree in International Relations. I'm interested in furthering my education in the UK, not soon, but sometime in the near future. I understand there is an immigration process and understand that bit, however how exactly would someone like me be admitted to a school in the UK? More specifically, England.

Does England have community colleges or equivalent institutions that would admit a community college student or graduate? What would the requirements be for an American student to be able to be admitted, in terms of units completed, credits, grades, etc.

Currently, my college does offer study abroad programs, however not to the UK. The current program (in Spain) allows students to attend a college in Spain with fellow American students learning familiar American courses and subjects. The difference is that they are in a different country. What I'm looking for is not to study an American course, I'm looking to study in the UK, studying a UK course (if that makes sense).

Thank you for the help! :-)