I have the same problem and even though I have newts, toads and the occasional hedgehog in the garden, the slugs were winning
I gave in and bought the wee blue pellets but they are in little domed traps that keep them dry from the rain and stops anything but something slithery like a slug or snail getting in.
I just go along in the morning and pick the dead ones up so that they don't poison anything else.
Seems to work, but I only use them in the tubs full of things the slugs adore, like my pansies, strawberries and so on.
The beer traps work too, but seem to end up full of beetles
swimming lethargically around, and the hedgehog seems to delight in getting into them.
I hate the idea of poison, but I really had tried everything else and nothing was effective.
Jaggy gravel, crushed shells, copper tape, aluminium powder and gel,
the blighters just kept coming.
Found edible snails in the compost heap last year.......kind of hoped they'd outdo the others and at least I could kind of crop them for folks who like them, but the tiger slugs and the grey backs and the yellow banded snails won out
cheers,
Toddy