I know that Brittany Ferries do not allow smoking on most of the fleet unless on outdoor decks, exception being the Normandie Express.

What is the situation at airports after check in? I guess they must be smoke free as well

Irish Ferries only allow smoking on one of the decks. i would assume that most ferries are the same now with the smoking ban.

Smoking rooms after check in, don't think so as if I remember right, even smoke rooms are illegal under the new rules. Smoke rooms are a good idea in theory but when the door is opened by someone wanting to go in or out, everyone nearby gets poisoned. Hubby and i were on the ferry that goes between Belfast and Stranraer, foot passengers have to go down the steps beside the smoke room on docking. We were told to go to the area beside the stairs in advance of the ferry docking. Hubby suffers from Asthma which although only very mild is affected by cigarette smoke. Even with his back to the door, he still knew when the door was opened. It got me as well as i'm susceptible to sore throats, I'd know about it the next morning after nights out at uni.

Norfolk Line Ferries, Dover to Dunkerque are totally non smoking.

Yes airport terminals are the same. No smoking once you've cleared security