Every month, I make a wire transfer through my UK bank account (HSBC) to my US account (Citibank). They say 6 business days but it's usually less than 3 days. I then pay online from my Citibank account. It costs £9 and I try to do it when the exchange rate is the best. All you need is the bank account number, the routing code from the bottom of one of your US checks and the name of the recipient as it appears on the account. Once you've done the transfer for the first time, the bank keeps the template so when you call up, they ask 'Have you done this before?', you say yes and it's all easy from there.
=)Cynthia