以下這句英文grammer OK? ”I shall work in Shatin today.”

"I shall work in Shatin today."is grammatically sound and good because I am telling someone what I shall do later. Even if it is 'today', I do not use present tense for something that is not happening now.

hi, if u are on the way to shatin, u can say ...
I am going ahead to Shatin and I will work for a whole day there.

Your sentence is not okay. It is a present tense. Therefore, no need to put "shall" there.

You should change it to "I am now working in Shatin."

not ok. you use present tense

what is your meaning??