I want to add my 2pworth here. I am in the same sort of boat as you mum2bean. I have really struggled to cut down from a 20 a day habit and got down to about 3 or 4 a day so far. My aim is to stop completely by the time I am 18 weeks.
THe stop smoking advisor told me that the best way is to set a date that you want to stop by and work towards it, changing your habits and gradually reducing your need for nicotine or just the habit of having a fag.
IT IS NOT EASY. The self-guilt trip has not worked for me at all. Every time I think about it I want another cig. However, if I don't think about it, I can easily go a full day without having one. THe biggest problem for me is extricating myself from the situations that trigger the stress reaction where I would normally say "that's it, I need 5 minutes to get away from you/this desk/this computer [replace with your stress trigger of choice]"
From the advice that I have been given, the last four months are the most crucial in terms of the development of the foetus lungs (I will be quite happy to stand corrected on this - but got if from the advisor) so if you can get yourself to a stopped position by the end of your 4th or 5th month of pregnancy, you are doing fine.
I am also not seeing any changes to my eating, so whereas my mum put on 2 stone after stopping smoking, my appetite is just not changing nor am I having an craving replacements.
The hardest bit for me has been everyone else telling me in a smug way, "I gave up the minute I found out I was pregnant" Good for you I say, but that doesn't mean that just because I havn't managed it that I am a bad mum to be or going to have an underweight, brain damaged asthmatic child.
A girl I worked with didn't find out she was pregnant until she was nearly 7 months. She went out and got p*ssed EVERY weekend, drank half a bottle to a bottle of wine every night, ate everything off the banned list, and smoked. Her baby was born a healthy 8lbs ish (cant remember specifically). I am sure that lots of women smoked all the way through their pregnancies - my nan did and had 4 very health babies. Whereas my other nan didn't and had 5 very small babies full term. A women at work, (much older that me) smoked 25 a day whilst pregnant with hers - no advice to the contrary - her daughter is now a law grad in fabulous health. THis isn't to say that every mum to be who smokes will have perfect children, but just to say that there are enough things to be guilty and stressed about while you are pregnant without putting extra stress on yourself.
The most supportive thing that some people have said to me is "well done for cutting down so much - keep it up".
The ironic thing is that the monday before we found out we were pregnant we had been to an appointment with the nhs stop smoking advisor together and put a plan together to stop.
Sorry, been a bit of a rant, but it is a very hard thing to do and to be honest, not really directed at any of you guys - just a bit low about it all.