"The timeless classic glamour tea dress"　sounds wrong? Should I change to A timeless classic style t

Both sound wrong. This isn't a complete sentence, and  a difference in articles won't change that. It could be made into a sentence with the addition of a verb, but you still have problems with the string of adjectives modifying 'dress'. 'Timeless' and 'classic' are similar enough to make using both redundant. Here is a suggestion, and either 'The' or 'A' would work.

The timeless and glamorous tea dress is appropriate for many occasions.

I agree with the first answer but would suggest another option.

The glamorous tea dress is timeless and appropriate for many occasioins.