Thailand in general has an excellent healthcare system, although you need to ensure that you have comprehensive medical insurance if you travel to the country, as free healthcare is not available to tourists, and the costs of medical repatriation from Thailand to the UK is very high.
Some areas of the country, particularly in the more remote areas have had cases Malaria and other mosquito borne diseases in the past, and it is a good idea to consult a doctor prior to travelling, and take appropriate measures to avoid insect bites.