Vicki
I grow landcress, it does very well over winter under fleece and I've also grown watercress, available from most seed suppliers, ie Chilton, Garden Organic etc.
I sowed it into water saturated compost in a container without drainage holes and kept it very wet, very quick to germinate and I got a good crop from it but did lose it in the intense heat of the summer when it went to seed.
Would certainly grow it again, I love the stuff.
Best wishes
Sue