My wife is under birth control , because she want to be clean in a planned vacation
My question is , if she needs to make a bdika Yom havest ? How about day 30 and 31
She will need the regular bedikos, because it is still possible that she will see.
As a side point you should speak to a Rov before taking birth control, especially if it is only for reasons of personal pleasure.
Best Wishes and enjoy your vacation