To break this habit, you will have to get up very early one morning (when you have plenty of time), and get your puppy out on a walk before it has had its morning wee. You should not bring it home until it has been forced to go out of desperation. If however, you are unsuccessful, and your puppy has not toileted, then take it immediately into the garden on your return, or you risk it relieving itself indoors. Need more help? Follow these additional puppy training tips (e.g. socialisation techniques to prevent behavioural problems) or visit the Puppy Socialisation Plan website.
A training class is not there to train your dog. Its purpose is to teach you to train your dog so you will need to be committed to train your dog for short sessions (5 minutes) several times a day rather than just simply turn up for classes! This little bit of training everyday will be repaid with a lifetime of living with a well behaved dog. You will also learn to avoid problems before they begin as well as receive help to overcome any that you already have with your dog.