We have two species of the prickly pear
family at the moment, the western prickly pear,
O. compressa, which is quite sprawling in habit but quite a bit hardier than most cacti. It can survive outdoors in the warmer parts of the UK but would need sheltering from too much wet and frost. A gritty, free draining soil is essential and they are likely to perform better with some extra heat, but as they happily grow in large pots, they could inhabit a conservatory or windowsill with pleasure.
Indeed, our other type will only survive indoors, the
indian fig, O. ficus-indica, is the type that usually supplies the fruit in your supermarket. More upright in habit, it has larger flowers and fruit but is less cold tolerant. Originally coming from the arid parts of the USA it has naturalised and become a problem in many parts of the world that suit it. At home in the heat, the big flat pads are not too spiny as cacti go, more like hairs, but care should be taken as they can cause irritation.
They both have beautiful big yellow flowers, hopefully followed by delicious sweet fruit from about 4cm in size which could be either yellow, orange, red or purple in colour. Just pick, peal and eat.