Domestic driving rules, log books etc

Road2ruin:
If you drive for less than four hours per day you ate exempt from the 11 hour duty limit. Usually domestic work within a radius of 50km from Base does not require a log book to be kept. And most exemptions no longer apply if you exceed a 100km radius although some do.

I drive for far more than 4 hours a day every day and all over the UK.
Sometimes its a 5 or 6 hour stint in a truck then driving back in a hire car which obviously doesn’t take quite as long due to no speed limiter etc. But often I’m returning in another truck.
I’ve started my own log book as my employer seems pretty clueless about the law. Whether that’s intentional or down to genuine ignorance I don’t know ?