Whilst on a search for useful information to make your lives easier, I came across this rather useful page provided by North Yorkshire County Council which details the timetable of term dates for the local schools.
The page also lists those Teachers Training and Development Training Days that can sometimes catch people out.
It runs all the way up to 2020 at the time of writing, allowing the super organised amongst you to book leave from work so far in advance that you are almost guaranteed to be a winner in the race to book your chosen time off work. You can have it booked before anyone else has got off the starting blocks.
Not sure if your children will thank me for letting you know when school goes back after the summer hols though.