If driving close to the speed limit in OPTIMUM conditions terrifies you so much, do stay off the road dear, for the sakes of all of us good and confident drivers
People who think they are good and confident drivers, are often nothing of the sort, they lack insight into their own bad driving, as you ve more than adequately shown.
If you want to enforce traffic law, join the Police, otherwise focus on your own driving instead of getting distracted (one of the more common causes of accidents) by other drivers.
The vast majority of UK A/B or designated 60mph roads are not straight nor dueled, they have bends in them, high hedges, cyclists, caravans broken down vehicles, on coming traffic.
So if your driving properly, you'll be slowing, anticipating... non of which you do, as you focus on speed and others so called bad driving.