Hi Sarah... on the basis that you've said you're garden doesn't get much sunlight, you'll want shade-tolerant plants (although you might want to check the patio area throughout the day - chances are it will get some sun at some stage). I'd recommend getting some hostas, ferns, fatsia japonica (castor oil plant) and perhaps a palm. These are all interesting to look at ("architectural" is the word), will happilly survive in decent-sized pots and require little maintenance. Think about grouping your pots in threes - this usually looks nice.