I'm buying a house from someone who has a dog and is a smoker. I am a
dog hater and non-smoker and am keen to remove any doggy/smoking smells
when I get moved into the house.

Remove and destroy all carpets (without exception) and curtains. Scrub all
walls and ceilings with sugar soap. Repaint every surface. They may look
clean now, but when you put a dab of new "Pure Brilliant White" next to it,
you may feel quite nauseous at the contrast.

If you must attempt to reuse the curtains, they'll need at least 3 washes at
60C, preferably in someone else's washing machine.

I'd be worried about the sofa. However, it is leather, so you might get away
with it after a good scrubbing. If it had been fabric, then it would be
straight in the skip.

Christian.