Do you want it all to be hardy stuff - plant and water once in a while. Or are you happy to tinker a bit more.
I like cottage garden style. For a shady garden more ferns, hosta, bluebells, snowdrops, daffodils, crocus and maybe a few acers in different colours and I like a few box plants too but i know thats mixing styles. Ivy around the edges / over trellis for a bit of winter green.
I don't know whats poisonous - is it for yourself/ children or the cats you're concerned?
Pinterest is good for collecting ideas and thinking about the hardscaping like patio/ seating/ barbeque areas.
I think cottage garden will suit my taste best, any tall plants have to be flimsy and not able to withstand a cat using them to aid jumping over a fence. I live on a very busy road so cats have to be contained with the garden
Also having looked at the sun at various times of the day the garden is not as shady as first thought.