They look somewhat like one of the sawfly larva.

Here is a link that might be useful: About Sawfly

#1 Tough to tell from the picture but I'd say sawfly larvae is a good guess.

#2 Looks more like currant than spinach

Perpetual 'Spinach' is Beta vulgaris, a member of the beet, chard family (Chenopodiaceae).

Huh, learn something new every day. If I heard it from anyone else I'd think they were pulling my leg. Sounds like something from dungeons and dragons.

"I smite the dragon and feed the entire village with my +5 of rusack of perpetual spinach".

(No, I did not date a lot in high school)

rusack = rucksack (sigh, not my day)

The little White bits don't move and are lined in little rows, an indeed it is a member of the chard family, ok raw, better cooked (IMO)

I did find a big catepiller today, no idea where that came from. :0)

Does the UK have sawflies?

BBC, garden pests - "Sawflies affect a number of different plants but different types tend to affect different crops. Some of the most common are the apple sawfly (hoplocampa testudinae), the common gooseberry sawfly (Nematus ribesii), the turnip sawfly (Athalia rosae) the pear and cherry 'slugworm' (Caliroa cerasi), the rose slug sawfly (Endelomyia aethiops), also known as the rose 'skeletoniser'. "

Oooh, sawflies are probably EVerywhere! But, I have to say that I don't really think that your pests look like sawflies, at least not to me. But my spectacles probably need adjusting.

Little caterpillars grow up to be BIG caterpillars in a few days.