You're clearly not looking hard enough on the internet.
VFS Global is what you need to Google and you can apply for a UK tourist Visa through this website. I have used it many times and you don't need an Agent, as long as you are capable of following the application process.
Costs involved are for an appointment and the Visa. Anything up to £200 depending on which VFS Global centre you select in Thailand. You can only apply online and at least your GF has to attend. You can if you wish. Good luck
Try to obtain a Residence Cert from Immigration and show this to the Bank. They may accept this and allow you to open an Acct. Maybe worth asking the Bank first, before you go to the trouble of obtaining the Residence Cert.
Google store links your location to Apps you wish to download now. If your Google location is Thailand, some overseas banking apps won't let you download them.
correct. They will ask you for your outbound flight details, IF they believe you are living here on the incorrect Visa. Immigration will then force you to buy an outbound flight, before letting you enter.
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