At the moment, all UK passport holders are entitled to 15-day Vietnam visa exemption. However, they cannot get visa exemption if their arrival date is within 30 days from the exit date of their last stay in Vietnam without visa.
So, what happens if they have multiple (3, 4 or more) stays in Vietnam within 3 months and each stay is less than 15 days and duration between each stay is less than 30 days?
If it is your case, applying for a 3-month multiple entry visa is highly recommended.
However, since beginning of 2016, procedure to apply for a 3-month multiple entry visa for Vietnam has been made a little bit more difficult, and not all online travel agents can process this kind of visa for you. But, Vietnam-visa.co.uk can do, and do it simply.
How to apply?
To apply for 3-month multiple entry visa, you only need to fill out the online application form at http://vietnam-visa.co.uk/request-form-form-3-month-multiple-entry-visa/. After receiving your request, Vietnam-visa.co.uk will contact you via email for payment of service fee. Then, you will receive your visa approval letter via email after 2 working days, and finally get visa stamped upon your passport at Vietnam airport.
However, the visa approval letter provided by Vietnam-visa only works if you travel to Vietnam by air. Otherwise, you will need to contact Vietnam embassy in UK or in any third country which is convenient for you to apply for visa to Vietnam.