I was reading an article written by a Hosta gardener. Slug/ Snail deterrent recipe. you boil two whole heads of Garlic for 30mins in a pint of water ( you can lightly crush the garlic). Cool and then bottle. Add one tablespoon of liquid to watering can, Water into the ground from the start of the growing season and throughout. The writer states that he now has very little problems with the little slimeys.
I tend to walk round the garden in the evening with a very small amount of salt, just 4-5 small grains(not enough to harm other wildlife) on each critter sends them to their demise. H also keep eggshells , heat them in the oven to sterilise , crush them (beware sharp) , pile generous amount around susceptible plants.