That website does look interesting Blackpudding, I'll have a better look at that later.
Heliotrope we started our club after Feb half term last year. We ran it one lunchtime a week, half an hour with key stage 2 and half an hour with KS1 to fit round their lunchtimes. Up to about 12 children at a time with 3 to 4 adults. We have four raised beds and a variety of containers (old tyres, sacks for potatoes, old plant pots). We kept a diary, which I would highly recommend. We asked for donations of any gardening stuff from parents and were given lots of old seeds and plant pots which got us started. One of our biggest expenses was compost to fill all the containers, but hopefully we shouldn't haveto spend as much this year. A water butt and lots of small cans are very useful, if there aren't enough other jobs to do on any given day children will happily water anything that needs it ad infinitum. We sold our produce at various fundraiers and parents evenings.
As for crops, we planted onions and broad beans at the begiining of March, both were very successful and were both ready to harvest in July. We also planted radishes in March, they were ready to eat in 5 weeks, but it was an exceptionally warm spring, we had a second crop ready to harvest by mid June. Salad leaves planted in March were also a great success. We planted beetroot in May which we were able to harvest in July too, they were very easy to grow. we also grew pumpkins, squashes from seed ready for the Harvest festival in October, and cucumbers and courgettes which were sold in July. Also swewet peas, nasturtiums and french marigolds in between e other crops
Things we won't be doing again are tomatoes - too much watering needed in school holidays, crop in August and ours got blight. Potatoes- maybe a few as the children enjoyed doing them, but we did about 40 sacks of them and didn't top the compost up high enough because we couldn't afford it, they didn't crop well and a lot were exposed to light and went green. Also, so many people grow them that they were hard to sell (also heavy for people to take home, parents would buy a bunch of radishes or bag of lettuce on the spur of the moment but not potatoes). Runner beans- we only grew a few and will do thesame again as they just didn't sell, anyone who likes them tends to grow them at home anyway and they are so prolific no one wanted to buy them.
We took lots of photos and entered our local town in bloom contest and won a gold certificate, so we have a lot to live up to this year.