The notches will be the work of the pea/bean weevil, and as you have noticed they have not affected you plants.
Slugs/snails the best way I have found is in two parts firstly I like to know where they hide out during the day, if I can't find this then the second part is I create places for them eg.
At the start of the season I put down a plank of wood on some convenient spot, tilt it on a couple of stones so that the slugs /snails can get under.
I let them acclimatise to this new abode for a few days then I trickle a few slugs pellets along the edge of the board so that on their way out they might have a taste,failing that I might get them on the way back.
All I have to do then is shovel them up.
Similarly if I do know where they hide out during the day I trickle a few pellets across the route they will take on their nightly forages.
What I have found now is although I have a few I don't have hoards of them, these I usually get by placing just a few around the perimeter of a newly planted bed.
I think winter digging helps as well because this fetches the slug/snail eggs on to the surface for my resident robin to feed on.
I don't expect to beat them but at least I have got them reasonably under control.