Actually not a problem anymore! If you get checked out by a vet specifically certified to make the determination, from Canada there is no quarantine. Found this out when sibling was in Wales. From here:

You can enter or return to the UK with your pet cat, dog or ferret if it:

has been microchipped
has a pet passport or third-country official veterinary certificate
has been vaccinated against rabies - it will also need a blood test if you’re travelling from an ‘unlisted country’
Dogs must also usually have a tapeworm treatment.