I suggest you go by train to Versailles on a day trip on your own instead & not by tour if your tour schedule doesn't include Versailles. Alternatively, roaming around some prominent sites within Paris by Metro (subway) to see more in depth is also good, if you are new to France or Paris. I have been to Paris quite a few times over the years, and still find the city a charming place to explore 😎
The 1 day tours are super busy. Just getting to the coast takes 2 hours min. each way. Or if you would go to Mont Saint Michel it's over 4 hours drive. So a good chunk of your day is lost sitting on a bus. And you won't get any chance to shoot with good light from a sunrise or sunset. Only way to do it - go and stay at the coast in one of the villages (and there are plenty). You can go there by train - but getting around requires a rental car. Things are spread out too much. No problem if you have a car with a GPS. And quite an experience.