In Canada the voltage is 110v, while in the UK it is 240v. So you will need a step up transformer to change the voltage from 110v to 240v.
But be careful if the electrical appliance has a motor that rotates (fan, etc.) it may not work (or work at a different speed) because there is also a frequency difference (Canada=60Hz, UK=50Hz).
Finally, make sure you also get a plug adapter so that you will be able to plug the appliance in the UK sockets.
Hope this helps.
Yes you will need a voltage transformer or converter that will convert from 110v to 240v for the specified wattage of the steamer (the wattage is usually marked on the machine (e.g. 1500 watts etc).
You can get that converter from any radio shack or electrical shop.