The US-UK Fulbright Commission offers special Summer Institutes for US citizens to come to the UK.  These summer programmes provide the opportunity for US undergraduates (aged over 18), with at least two years of undergraduate study left to complete, to come to the UK on a three, four, five or six week academic and cultural summer programme.

Participants in these programmes will get the opportunity to experience an exciting academic programme at a highly regarded UK University, explore the culture, heritage and history of the UK and develop their academic ability by improving presentation, research and communication skills.

UK Summer institues: 

http://www.fullbright.org.uk/fullbright-awards/exchanges-to-the-uk/undergraduates