Next one a simple saying but what is the correct thai way I know next time next week are straight foward so would a direct translation one next un nah or nueng nah be correct

It depends what 'one' is. Don't forget that Thai uses classifiers for different things so a generic word such as this might not be used. If you gave us a bit more context to your example it might help.

Next one as in person in line

The general classifier for a person is simply คน khon

คนต่อไป khon[MS] taw[LL] pai[MS] (the next in line [the following person])

คนข้างหน้า khon[MS] khang[FS] na[FL] (the person in front [of you/him/them etc.])

Transcription note: 't' and 'p' in my transcription represent unaspirated, unvoiced sounds. Some people indicate these as 'dt' and 'bp' to show that they are not the same sounds as 't' and 'p' in English. Like the AUA and Mary Haas transcriptions based on the International Phonetic Alphabet, I use 't' and 'p' for unaspirated sounds, in contrast to 'th' and 'ph' for aspirated.

Unaspirated = takes no puff of air afterwards.

These are also different to 'd' and 'b' in that they are not voiced = the larynx does not vibrate when pronouncing them.

The 'aw' is reasonably similar to the sound of 'aw' in the word 'law' as pronounced in US English.