My friend, who has been here on holiday for a month, will visit Vietnam for 2 weeks. He will then come back to Thailand on a 30 day exemption. Is it possible to extend that for a further 2 weeks if he goes to immigration? He has a British passport.
TLDR : Answer Summary
A British passport holder can enter Thailand on a 30-day visa exemption and may visit Vietnam. However, extending the exemption for an additional 2 weeks (14 days) is typically not allowed under standard procedures. Your friend should check with the local immigration office in Thailand for any possible options or policies that may apply.