Slightly duff advice there. The A25 autoroute passes through the Lille ZPA.If you are not riding into the center of the major cities on the Critair list, you should be fine, going around them is fine, and if you get stopped get your 68 euros ready for a bike or car.
https://vignette-critair.com/vignette-crit-air-toutes-les-villes-concernees
A crit air sticker cost about £4.50. What's the problem?