If you go.over 15 hours even by 1 min then that’s illegal anyway.
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Way I do it on.the odd days when don’t do much driving time.
do.upto 6 hours before need a 15 min break. Then take a 30 min break before 9 hours.
Although bear in mind if you take your 15 min.break say after 2 hours. 6 hour rule still applies.
So you start at 6 work to 8 have a break of 15. You will need another break at 14 15. At be 6 hours since last break.
Way I do it anyway if it suits and don’t do much driving during the day
And never realy on what any manager says about your working hours time .