United Kingdom is in the exemption list for Visa to Vietnam within 15 days. Therefore:
If you stay in Vietnam less than 15 days, visa to Vietnam is NOT REQUIRED
If you stay in Vietnam more than 15 days, visa to Vietnam is REQUIRED
Citizens or residents in United Kingdom can choose one of three options below to apply for a visa to Vietnam:
For apply for a visa online, you have to pay two (02) kinds of Visa Fee, which were called Service Fee and Stamping Fee.