If they reduce the entry stamp back to 30 days, due to the fact I have already bought my ticket for a 40-day stay, I will pop into a Thai embassy in Chumphon and get an extension, apart from proof of a ticket back to the UK, my passport, and 1900 bhat what else to I need to take
TLDR : Answer Summary
When planning to stay in Thailand for longer than your initial visa validity, it's essential to know the correct procedures for obtaining a visa extension. While there's a discussion about possible changes in entry stamps and visa durations, the current situation suggests that applying for a tourist visa before traveling is the best approach. To apply for a visa extension at a local immigration office, you'll typically need your passport, proof of onward travel, and a fee (usually around 1900 baht). It's also advisable to stay informed about any changes in visa policies and prepare for possible requirements like the TM30 form.