I would like to ask one question, please. Is the book for F6 June 2015 exam sitting with the validation date from April 2014 through March 2015, still ok to use for preparation for June`s exam or shall I purchase a new edition?
No you do indeed require the FA 2014 edition! I would suggest, however that the OT course notes are sufficient for you to study from along with the course lectures, but you will definitely need to purchase a revision / exam kit from one of the approved providers.