One other thing to be aware of if you are considering getting through an undergrad degree in the US (say in 2 or 2.5 years) using AP credits and dual enrollment, is that Oxford and Cambridge allow existing graduates to do a second undergrad degree in 2 years. See http://www.ox.ac.uk/admissions/undergraduate/applying-to-oxford/second-undergraduate-degree
This was traditionally what Rhodes scholars would do, although nowadays it is much more unusual.