I have never been asked when I had it. Probably because they saw I had it! When I returned one way on a retirement visa they questioned it until I showed the visa.
I use google map, check before starting out and it will find the fastest route. It can change throughout the day depending on construction etc. it will even give an option to revise a faster route on the way.
I am amazed the government has not made a clear breakdown of how it will go? Maybe they want to spring the bad news at the end of the tax year. I hope not but I definitely have a plan B.