okay, to get married in thailand you can come in on any visa or even a visa exempt entry. You're going to need to get an affidavit of freedom to marry from your consulate once you're here, then get that translated into thai along with the data page of your passport and get those translations certified as accurate by the Ministry of Foreign Affairs Office here.
THEN you and your thai bride to be go to an Amphur Office (like a city hall) and register your marriage.
This is how you get your affidavit of freedom to marry if you are a brit here:
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