British nationals are required to must have an ESTA travel authorization in order to enter the United States by air or sea without a visa for tourism, business, or transit.
The processing of an ESTA can take up to 72 hours. It is also advisable to check the status of an already approved ESTA in advance of traveling to make sure that it is still valid. All applicants requesting an ESTA will be charged for the processing of the application. The fee is $4.00.
How to pay no more than the $21 fee. Everyone from the UK going to the USA by air or sea, even those just passing through, must fill out an Electronic System for Travel Authorisation (ESTA) form in advance.