Q:

Accommodation while driving from Calais towards Paris

What are budget options to spend the night somewhere on the way between Calais and Paris while driving the motorway (closer to Paris ideally)? Are there any affordable hotels at the motorway services? Should we book one of these in advance, or just show up? We need a triple room.
We will have our camping equipment with us, so even a camping or bivouac site close to the motorway would do. 

A:

You have two possible toutes: the A1 via Lens or the A16 via Amiens.
Whatever the road taken, I suggest you have a look at Accorhotels (I am not affiliated with them). They have plenty of hotels all over France, for every budget. Amongst others, they have quite cheap hotels next to motorway exits, which are straightforward to find. Just check their map. There is an important concentration of (budget) hotels in the Île-de-France, before reaching Paris. 
Given the number of hotels it is not necessary to book long in advance. However, by booking in advance you may have a better price and you will be sure to have a bed at your arrival. On the other hand, if the first hotel is fully booked, the receptionist will be glad to help you and point you to the next hotel with free beds.  

