Thai visitor UK
Any Thai citizen wishing to travel to the UK will require a visa before making travel arrangements. Every day the British embassy Bangkok issue visas to the UK for Thai people, but visas are also refused every day. This is why it is best to obtain a Visa to the UK before making travel plans and paying airline fees.
Thai visitor UK
The British embassy will issue a visa to allow a Thai visitor UK though much information will need to be provided at the time of the visa application to proof the Thai citizen wishes to visit the UK for tourist reasons, also evidence will need to be provided to demonstrate the Thai citizen has good reasons to return to Thailand after visiting the UK