What is the best time to cycle during the day (traffic)? I started cycling a year ago and I have a favourite route for my time trial training since it is very hilly. However, I cycle on a major road (just outside town) and thus I like to cycle when it is less busy- both to avoid annoyances of having to come to a complete stop at roundabouts/traffic lights, as well as reducing the chances of getting clipped and in general being subjected to dangerous driving.

I live in the UK in a medium sized town, I believe around 120k~ people. So during rush hour, it's completely impossible to ride consistently anywhere. Since I am not a morning person, I have resided to cycling mostly in the evenings, around 8-9pm. But sometimes I would prefer cycling during the day so my question is the following:

What times of day do you usually find traffic most suitable for road cycling? 

I realize that traffic varies, but there are still some general patterns that I wonder about: public holidays, Sundays, weekends in general, school-related traffic and so on.
For the UK there are traffic statistics available. This graph from the 2015 Road Traffic Estimates shows the general trend for cars.



There are detailed tables of traffic flow available.

There is also geographical data available in the form an interactive map. This isn't broken down by time of day, but should give you an indication of which roads generally carry more traffic.

If you're interested in when is the safest time to use the roads, there are statistics on road casualties by hour of day in this report (page 153 - Reported casualties by day, road user type and hour of day).