What Im going to say is my very personal opinion, which everyone is entitled to, but I'm prepared not everyone will agree with.
Before discharging us from the hospital, few midwifes who were caring for us kept asking if anyone in our household smoked. We said no one did. Then they kept asking if it's likely we were going to have visitors who smoked, we said yes that's likely. They then spent no less than 30 mins explaining how very important it is that visitors don't smoke 2h before coming to see the baby, change their clothes, wash hands and brush teeth. Like I said, it wasn't just one person telling us that, but as our discharge was a bit lengthy, it had been handed over to 2 other mw, who all stated the importance of it. We were also given leaflets and handouts on third hand smoking, which I'd never heard of before. We came home and I did lots of googling about it. NHS advise is to keep baby away from second and third hand smoking.
I'm quite ott generally about certain things, but when I had my baby, all previous ott paled into insignificance. I knew if a friend wouldn't be understanding about smoke and my worries, not a big deal of losing such a friend (well tbh I haven't got a single smoker friend, but my dh has). My dh was fully on board, and he has plenty of smokers among his family and friends. We politely asked them not to smoke before coming over. If someone just popped in without much of a notice, I pretended I had to feed a baby in another room and would have refused handing him over if they'd insisted. What's more important I thought, being thought of as a rude ott nutter, or my baby's health? I couldn't care less what people would think of me. He is my precious little baby and I'd do what's in my power to reduce the risk of any problems for him. Im fully aware I can't control everything, but that's precisely why it becomes so much more important to control whatever I can.
IMHO, you are doing the right thing by planning to shield your baby from the risks of second and third hand smoking. Your baby is going to be very lucky to have such a lovely mum.
Congratulations btw and good luck with birth.