http://www.britainusa.com/visas/articles_show_nt1.asp?i=65025&L1=41000&a=41448 .only one hand carry bag is allowed. no need to have transit visa if you are on a valid student visa and can enter the USA again. well I was on F1 and just came back from a trip to Nepal on Jan 02 thru Jan 22 2007. my route was PHL-LGW-DOH-KTM and same route back. FYI--> LGW= London Gatwick Airport more on the link.