hello. i am a us citizen currently living in texas. my fiancee is a british/eu citizen living in belfast, northern ireland. i am planning to apply for a volunteer visa and have all the required documents. once i'm living there, what is required for us to get married? since i would be over on a volunteer visa, am i allowed to marry him? or would it be easier to apply for a fiancee visa before going over?

any help is greatly appreciated.