It is your responsibility to know the entry requirements
Imagine the scene: you have been looking forward to your holiday for months, the journey went smoothly, you're off the plane and have arrived at customs, but you haven't got the right visa and you're about to be sent home. Not quite the holiday you dreamed of.
This scenario might not just be a bad dream; it could happen to you if you're not prepared.
The basic rule is not to leave it to the last minute. Whether you need to renew your passport or apply for a Visa, it could take a couple of months so make sure that you start the procedure as soon as possible after booking your holiday.
It is your responsibility to obtain the adequate documentation in time, and embassies will not issue emergency documents just because you booked a last-minute holiday!
Entry requirements vary widely from country to country, also depending on your own nationality. European citizens travelling to other European countries will require little more than a valid passport, but they may be asked to register with the local authorities if they stay longer than 3 months, as is the case with Spain for example.
To travel to Thailand, your passport will need to be valid, not only for your intended stay, but for a further 6 months, and for 30 days after your departure date for South Africa, while some African and Asian countries will require specific vaccinations, such as yellow fever in Vietnam.
If travelling to the US, the Visa Waiver Programme (VWP) has a simplified process which allows British citizen passport holders to stay in the country for up to 90 days without a visa. You will, however, need to provide details of your journey at least 72 hours before travel through the Electronic System for Travel Authorisation (ESTA) or you will be refused travel.
It is important to understand that there is no room for negotiation when it comes to entering a foreign country, so don't hope to be able to convince Borders Officials to look the other way. It definitely won't work!
The easiest way to find out the entry requirements for your holiday destination is to look at the travel advice provided by the Foreign and Commonwealth office (FCO). They provide up to date travel advice, including entry requirements for British nationals for over 220 countries worldwide.