ATMS are common and easy to find. Most ATM’s have an English language option. Warning: ATMS in Thailand dispense the cash before you remove your card. Make sure you take your card from the machine.
There are a total of seven ATMs in the side street outside Serm Thai: Krung Thai, Bangkok Bank, TMB, Kasikorn, Government Savings Bank, SCB and Siam City Bank.
There is also a Bangkok Bank Branch close by in the same street. (Bangkok Bank is agent for Western Union.)