Keep fed and watered, but not waterlogged, place in the sunniest, hottest spot you can find. As winter approaches, remove the plant to shelter, either in a greenhouse or a cool room indoors, and take off the top growth to allow the plant to rest. In the spring, turn out, divide the corm if it needs it (it probably will) and repot to start the growing process all over again indoors at first, till risk of frost is past.
That's what I'm supposed to tell you - in fact, I left mine out in their pots on the balcony (south facing, sheltered) all winter (pushed back against the wall so they didn't get too wet and rot) and they're growing again this year, except for one, which was left at the front of the balcony and didn't make it.

If you have well-drained soil and you plant them deeply, you can leave the tuber in the ground. How wet and cold is Lanarkshire in winter? I think it must be the wet which kills them as our cannas survive year after year despite minus 18 to 20 for the last couple of years.

Thank you both for the info.....Do you think bark as a top dressing is unwise for this plant then?

If in the ground it'll be okay during the summer, but may mean too much wet in the winter, if that's what you mean,not sure what your worry is about the bark. Most people grow them in pots anyway.

I just thought bark might keep the compost too moist that's all. Thanks for your response Bamboo.... One final question....- part of the tuber was exposed when I bought it and I have left it that way.....Should it be completely covered??

Well mine are, and were when I bought them, though if left to their own devices, the tops of the corms do sit pretty close to the top of the soil.