What's the cheapest car to insure for for my son and his wife returning to the UK from abroad?

My son (48) and his German wife (56) are returning to the UK from Canada. I understand most insurance costs do not recognise NCB obtained from abroad. What car would you recommend to start the NCB ball...

What's the best small car for a newly qualified driver?

My son needs a small car as he's a new driver. What do you suggest as a first car as low purchase cost and low insurance? We were thinking of a Volkswagen Polo.