Woodlice won't have eaten your lettuce and pak choy if they were actually growing, they only eat decaying plant material as their mouth parts are too soft to eat through growing leaves. So it is something else eating your veg. could you take a photo and add to the question and include the little beetles too.

What did you fill your raised beds with? Home made compost, bought in compost?

Here in the desert, woodlice will eat very small seedlings, though Bok Choy is normally a bit robust for them. Even with lettuce seedlings, if the seedlings had more than 1 or 2 true leaves, I would suspect some other culprit. When sowing small seeds directly in the garden, we usually use some diatomaceous earth to reduce the numbers of woodlice, crickets, earwigs, etc.

What sort of earth is that, Tug? I looked it up & it said 'single celled alga'.

No doubt you have used wood formers to make your raised beds. The wood is now soaked to the max and is maintaining quite a damp condition which is indicated by the increasing numbers of woodlice. They are harmless to your veggies. Are you overwatering? Also, do you have a membrane covering the bottom of your raised garden. This will cause slow drainage.

Diatomaceous earth is mined from a deposit of fossil diatoms. While alive, each microscopic algal cell protected itself with a beautiful perforated and prickly shell of silica (glass). En masse, these fossil shells make a powder that irritates the breathing apparatus of many garden pests. It works best dry, so it should be applied every evening for several days after the seeds sprout, preferably until they have several true leaves. Pelleted forms are sold as a filtering agent in swimming pool water systems, but those aren't effective on insects.

Thank you everyone for your helpful answers