I've finally found where the slugs are hiding in my kitchen, I spotted one sliming it's way behind the cladding in the gap the grout left so I salted in front of it as it is a bit close to the baby gate for me to risk pellets.
The next day I had nothing but the day after I had 3 dead slugs. I kept salting it in case there were more hiding and now a week later I have had 8 altogether, sometiems 2 or 3 days go by with nothing and then the next day, more corpses for DH to deal with!
How many could there be?! They can't be getting in from outside to there as it is a stand alone wall so there must be a nest [shudder].