A lot of UK insurers tend to stay away from drivers who do not hold a UK/EU licence. This is probably because the laws are not the same for countries such as Canada, Australia and the US which makes it even more difficult to follow up claims outside the juridistion. There have been many cases where people just left the country after an accident and the car insurance company had to take the responsibility to fulfil the claim thereby making huge losses.
With an International Driving Licence (IDL), you are able to drive in the UK for a maximum of 12 months and you can get insured on that licence even though it was obtained in a different country besides England. However you will need to have the car registered in your name to be eligible for the insurance cover. Some people have changed their registration certificate in the past to overcome this problem and allow their fellow relatives to drive their car in the UK. This is one solution although not the most ideal one.