I know slugs and snails hate copper but that can be expensive, Place a copper ring around plant and it repels slugs and snails
A good idea for slugs is to place a sheet of plywood or something near the area they will hide under it during the day.
for caterpillars there are chemicals that kill them and a vegetable oil called neem.
Neem kills pests like white fly too, but can also kill bees and earthworms
Attracting birds is great for caterpillars, place bird baths or hang bird feeders above or near you plants
Plant herbs and flowers around your garden to repel caterpillars. Many insects dislike the scent of lavender, mugwort, sage and peppermint
Hope you can use any of that