Spread a circle of ash or grit around seedlings. Slugs and snails don't like them and will keep away.
Sprinkle salt on slugs to kill them. Stage an evening raid in the garden, salt cellar in hand; sprinkle each slug once, then again in 5 minutes.
Slugs and snails can be easily captured in an empty half grapefruit inverted on the soil. Leave it overnight and they will have congregated inside.
Slugs in the house