When you prepare for relocating to Thailand, consider attending a Thai class. Admittedly, Thai may be a bit tricky for expats whose native languages are not tonal or who do not distinguish carefully between various registers, such as street Thai and religious Thai.
But you are bound to make a better impression as a foreign resident living in Thailand if you try to pick the basics of the local language. Expat children are obligated to take Thai classes in school. This rule applies even if your children attend a private or international school during their life in Thailand.