1. Vietnam Visa Vietnam has visa exemptions for British tourists for up to 45 days. 2. Cambodia Visa British travelers need a Visa to enter Cambodia. Here are some options depending on your cruise direction: Upstream Cruise Your cruise line will assist with visa-on-arrival processing at the water border. Cost: 37.15 GBP - 55.75 GBP/person Required: Passport (valid for at least 6 months), 1 passport-size photo, cash for the visa fee. Downstream Cruise You will need to obtain a Visa on Arrival at one of Cambodia's international entry points. Available at: Major international airports (Phnom Penh, Siem Reap, Sihanoukville) and certain land borders. Validity: 30 days (Tourist Visa - T class) Requirements: Passport (at least 6 months validity), 01 passport-sized photo, Visa fee (around 22.29 GBP - 26.01 GBP), and completed visa application form (available at the airport/land border).