As you stated hypnotherapy
has helped you in the past to quit smoking
, then taking hypnotherapy at regular intervals along with proper medication to reduce withdrawal symptoms
will definitely be useful to you.
You can learn self hypnosis
easily to change negative thinking to positive ones which will have major impact in this case.
Make a few positive ( Affirmative ) sentences related to quitting your smoking habits which you should repeat all along the day whenever you remember.
It will help you a lot along with medications. Hypnotherapy have zero side effects. All it can have positive results or nothing at all but no side effects.
First, you have to believe that quitting smoking is a possible task for you, make your subconscious mind to believe the same with the help of self hypnosis & you will surely get fruit out of it.
All the best.