would i use the word ' moc'
"Moc" means 'strength' or 'power', not 'may' or 'might'.
You can use it for physical strength or mental, same as in English, you can even use it to describe strong wodka ;)
'może' is the word I think you are looking for, meaning 'might' or 'may'.
i might not go there today =
może pójdę tam dziś.
i may want to see you today =
może będęą chciala cie zobaczyć dziś.
you might not like it =
może ci się nie spodoba.