The UK Embassy in Bangkok warns its citizens that the situation is unpredictable.
On its website, the embassy said that political demonstrations continue in and around Bangkok and elsewhere in Thailand. Some of these have been violent, including the use of gunfire, and there have been some casualties.
"The situation is unpredictable, and further protests are expected. There have been calls for an increase in protest action from January 13, which may cause major disruption to travel on main roads in and around Bangkok. You should avoid all protests, political gatherings and demonstrations."
Full report is here: https://www.gov.uk/foreign-travel-advice/thailand/safety-and-security