Your application for a Standard Visitor visa should be made no earlier than 3 months before you intend to enter the UK, and it will generally take no more than 3 weeks for the visa application to be processed and a decision made after your appointment.
If you have a BRP and you leave the UK and want to re-enter you will need to show it at the border (along with with your passport) to confirm your immigration status. Please note the biometric residence permit is not a travel document on its own and therefore will need to be shown alongside a passport at the border.
It can take up to 14 weeks to get a decision once you've submitted your application and sent any supporting documents.
Travel documents are primarily used for international travel. They serve as an alternative to a national passport and are essential for crossing international borders if the country recognises it.
ESTA applications may be submitted at any time prior to travel. 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.
If you are outside the U.S. for one year or longer Use Form I-131 - Application for Travel Document. For permanent residents, the re-entry permit is valid for two years from the date of issue. For conditional permanent residents, the re-entry permit is valid for two years after the date of issue.
Passport, Travel Visa and National ID Card You can even consider having multiple documents such as your passport, national ID card or driver's license.
Advance parole allows you to travel back to the United States without applying for a visa. A transportation company (airlines) can accept an advance parole document instead of a visa as proof that you are authorized to travel to the United States. An advance parole document does not replace your passport.
Use Form I-131 - Application for Travel Document. For permanent residents, the re-entry permit is valid for two years from the date of issue. For conditional permanent residents, the re-entry permit is valid for two years after the date of issue.