Ride longer next time! On a typical tour I am in the tent falling asleep by 8-9pm because I am so tired from the days riding. Once you wear yourself out sufficiently it's easy to get to sleep.

You are brave to just go for it like that, especially for your first tour. If you plan to go on longer tours, especially mountainous ones, you should be prepared for temps in that range, as I have experienced them even in July. My suggestion is to carry one full set of layers for off the bike that will be good down to freezing or just below. I never really regretted having them on any tour. Last July I thought it was ridiculous to have so many layers in the center of France until I stumbled upon temps just above freezing....very glad to have them in the end.