Bangkok

The local currency is the baht. You can exchange your pounds/dollars in banks and in foreign exchange offices, in the daytime and at night for some. Every day, even the weekend.

On the other hand, if you withdraw money to the distributors, you will have a tax (approximately 150 bts every time). Thus, it's better to remove big sums at the same time. (By paying attention to maintain your money in good safety).