Once you have been accepted to that school, get the paperwork flowing. Also allow tonnes of time for the visa. Again, if you're doing this in summer, the queues get longer at visa offices. This is not to say that you want to lie on your forms, but just be aware that an undergraduate in even the top university in America simply does not have the same skills of independent study that their British counterpart does. Much spoon-feeding goes on, even at Masters level, and this can be a bit of a shock for students from the UK who are used to having a few detailed essays every term, with lots of time to get things sorted out.
Many courses demand weekly papers, preparation and sometimes tests and quizzes every few weeks.
Other times it feels like you're back in Primary school. It all just takes getting used to, and will not be the case at all universities and in all departments. In fact, it simply made me tired, in a similar way that I would have been tired if I was speaking a foreign language all day. After all, that's what it is. Then if people don't understand you, they will ask.