Can i travel to usa from uk without an esta?
Yes (if you have a valid green card or VISA). ESTA is a free, automated system that determines the eligibility of visitors to travel to the U.S. under the Visa Waiver Program. If you are not travelling to the USA under the Visa Waiver Program then you do not need to complete the ESTA process. This assumes you have a green card or a valid VISA for the USA. If you are travelling for vacation or business and it is for less than 90 days then you probably want to travel under the Visa Waiver Program and complete an ESTA application (it’s really easy).
No, effective June 3, 2008, if you are a citizen of a country under the Visa Waiver Program, including the UK, then you do now need to fill in an ESTA online form 72 hours before departure – it is ultimately going to replace the Green I-94 form that you will also need to fill in before clearing passport control in the US. If you aren’t from a VWP country, regardless of where your flight departs from (i.e. the UK) you will still need to apply for a Visa. I am assuming you are a UK citizen and therefore you will need to fill in an online ESTA form – it is very quick, and you only have to enter the starred (*) information, and then it is also valid for 2 years covering and subsequent trips. You ARE required to obtain pre-approval for entry to the United States before boarding your flight/ship for the US, although it does not guarantee entry to the US upon your arrival.