Best route to avoid Rouen LEZ driving to Calais

I'm seeking advice on the best route to avoid Rouen to reach the Calais Ferry now that the whole of Rouen has been included in their LEZ. I have 2008 diesel car so it's not compliant under the new regulations. The same problem exists with the London ULEZ but the M25 is still free for now.
My Garmin that avoided Low Emission Zones recently gave up the ghost and the only replacement I could find locally is a TomTom GO from Mediamarkt which does not have this facility! I'm hoping someone has experience of bypassing Rouen and can offer some good advice.

I don't know where you have got you information from but currently Rouen is subject to a minimum of Crit'air 3.

https://urbanaccessregulations.eu/countries-mainmenu-147/france/rouen

For petrol cars that applies to Euro standard 2 & 3 cars manufactured between Jan 1st 1997 and Dec 31st 2005.

For diesel cars it's Euro standard 4 which applies to cars manufactured between Jan 1st 2006 and Dec 31st 2010.

Your 2008 car therefore qualifies for a Crit'air 3 vignette which you can apply for from Spain.

https://en.wikipedia.org/wiki/Crit'air

Hi if you pull up a map of the Rouen LEZ and enlarge it, you will find that there is a corridor through it.
You can also apply on line for a critair sticker for France,which we did, it’s about €4 but it took 6 weeks plus to get it.
The French stickers are also valid in spain, just in case anyone’s driving a non Spanish car
Hope this helps.

Thanks for your advice. I'll have another look at the Rouen map.