Murphy's "English Grammar in Use" - Cambridge University Press is great - good clear modules with illustrations and a few check questions at the end. I haven't used it online but the book is available usually at the Foreign Language Bookstore in Melbourne. I just searched and found this link: http://www.cambridge.org/au/elt/catalogue/subject/project/item404854/English-Grammar-in-Use/?site_locale=en_AU Grammar is great Good luck