Car Insurance Canada

we arrived in Quebec and a plan to buy a car and go to New Brunswick, we have a driving license in the United Kingdom. Thank you for any help!

As landed immigrants, there is no difference between you and the citizens, for insurance. The only difference, really, is that you must have received your immigrant visa with you and your UK passport to enter and leave the country.
You must pass the Examination Canadian driver's license within 3 months of being here. Your licenses in the United Kingdom are good so far.
BTW, I would never buy a car in Quebec. They have the most relaxed laws in the country, which constitutes an "accident" or "dangerous" car. This is where our car was wrecked after we were paid by insurance. Use caution, even if the car is good. Get a CarFax report before you buy, if you know it has not been reached.