LoveFilm - Outstanding Discs

Hi, I cancelled my LF by Post membership around a month ago, I believe that you have 30 days after cancellation to return any outstanding discs (I have 3x blu-rays). I was supposed to send them before the bank holiday weekend but forgot, 30 days will be up on either Sunday or Monday - I was wondering what happens next? Will I get charged somehow or will it be fine to post it to them on Tuesday?

Thank you