Tagging on for interest..Our local schools do this with veg plots...But plant with crops that need harvesting when the school is closed for the holidays!! Everything gets spoilt.

Need a bit more info - when you say its fully accessible by young children, do you mean they'll be climbing up onto the raised bed and running around in it? How big is the area and what part of the country are you in?

Thank you for posting Bamboo... hopefully they won't be climbing all over it (fingers crossed!) but it is at the edge of the playground so they will be around it and be able to make contact with the all the plants so no spikey or poisonous or irritant plants. The initial bed is 1.8m by 0.9m but it is hoped that another can be built when resources allow. I am in North Shropshire about 20 miles west of Stoke on Trent.

Pretty small then - more a row of plants, really, at those measurements, which will be twice as long as it is deep from front to back. As its so small, it'll be difficult to achieve height because of not being able to use so many plants which might be toxic, and because it's shady. I can think if smaller perennial plants such as Lamium maculatum, Brunnera, Polemonium, Pulmonaria, Primrose/Primula/Polyanthus, Ajuga reptans, Fuchsias but evergreen shrubs which tolerate shade like Fatsia, Skimmia, Camellia will take up most of the space available, so taller evergreens will be difficult. Campanula persicifolia will probably cope with the shade, and flower, as will Campanula portenschlagiana. These two will at least have green close to the ground all winter. There is Fatshedera variegata or aurea, but it will need staking, doesn't support itself, but at least looks good in winter.
If I think of anything else I'll come back to this thread.

Thanks Bamboo, not having year round height is not a problem - I will go and read up about your suggestions, I recognise a few but not all (love pulmonaria but hadn't occurred to me to use it here!) thank you very much!

There's Geranium too, the cranesbill ones, but they can look pretty tatty during winter.

I don't think most of the things you mention, Bilbo, will do well in shade, unfortunately.

Why not try some of the different scented mints? They do well in shade, also Lemon Balm. The kids will love the smell.

Sorry I haven't responded sooner... plus the last comment I wrote doesn't seem to have worked so.... there are already raised beds with lots of sun that are used for veg/sunflowers etc. (and a small polytunnel is about to go up!) so that sort of thing is already covered, this bed can be whatever else we want to do. Love the mint and lemon balm idea, gives an extra dimension sensory-wise!! Thanks again!

Erm, I wouldn't recommend mint, frankly - it'll take over the whole bed in no time, best contained elsewhere. Lemon balm, whilst nice, is fine if you're prepared to be vigilant with weeding - it seeds like the devil and takes over, although its easy to pull out, unlike the mint.