You can do within Thailand as long as you have at least 2 weeks left on the current tourist visa (exempt / extension) but applying from outside and especially home country is so much easier…. At least as I assesed at the time in my case after enquiring with two IO: Jomtien and Sriracha.
body wash and washing up liquid? I see aisles and aisles of it at supermarkets …. I usually buy natural and biodegradable … this washing up liquid is certainly very good