ok my experience on quiting smoking.
Firstly i have not used champix as it wasnt out when i quit but heres my little story anyway.
I stopped smoking around 2-3 years ago after smoking for around 8-9 years (a box a day). Went cold turkey and honestly it was the best way to do it. My willpower is well.... i always have felt there is nothing i cannot do. especially quit smoking. I felt similar to the way you have mentioned, got to a point where i was saying to myself why am I even doing this? Every drag i would take would make me feel a little sick and i wasnt actually enjoying it anymore. I think i took a serious look at what the reasons were for smoking and how my health was being affected and the amounts of money i could use else where. At that point in my life i was still quite young(not that im not still very young) but i didnt have a job and honestly wasnt sure how i was affording it anyway. Both me and my gf decided it was time to quit and we smoked our last 1 at night when we went to bed and then woke up with none and just never bought again. I have had 1 smoke in the last 3 years and that was 6 months after i quit. It wasnt even a full smoke, just a drag or two then i felt sick.
How did i get over the feeling of needing the smoke? or how did i break the habit? Honestly at the time the reason for smoking was to cover other smells in the room(i smoke weed and i still do). Every single time i felt like a cigarette i picked up the bong and well got high instead. Sure sounds like a stupid idea? BUT no one has died from weed according to my knowledge as of yet. My weed consumption went through the roof for 3 weeks while i was getting over wanting a cigarette. Was smoking like 10 bongs a day which was stupidly crazy but hey it worked. I still smoke weed but the consumption has dropped drastically, back to like 1 or 2 bongs a day unless gaming

but thats personal preference, i dont NEED the weed, i enjoy it and it relaxes me after a hard days work. If i wanted to stop weed i would do the same with cigs and go cold turkey although i dont feel i would need to replace the habits with something else as it is not a habit for me, some days i have none and still feel fine (maybe a little edgy)
My personal tips are to not smoke at all in the first 3months of quitting, if you do you will have "lost" the battle. Never lose the mindset of do not smoke.
When my parents smoke around me now i feel sick and it smells so disgusting i actually dont know how i started!
My health has improved alot since stopping cigarettes, From being sick almost monthly i now get sick maybe once twice a year.
If you are to quit smoking i would suggest going cold turkey and just push through the rough period (a few days/weeks depending on person) as you know you dont have some strange pill doing weird things to you like giving you depression, You know you have conquered this with your own willpower. It might be tough but i am confident anybody can conquer this with willpower and i wish all the best to you on getting over smoking
madh4tt3r