It's a real shame, and seemingly quite odd, that the age requirements for the IEC differ from the UK to France- I really thought they had been aiming to fix these inconsistencies.The IEC programme is for people in the U.K also but that is shut at the minute (although it must be close to opening up again). I am also not sure they would grant that visa for somebody in the middle of a PR application because the point of the programme is for people to experience Canada on a working holiday so I doubt very highly that IEC would be granted with spousal application in progress. Even if it were open it would still take a matter of weeks to be granted the visa, am I correct? Also just checked the website and applicants from the U.K have to be between 18-30 and not 18-35 like some other countries.
The IEC opens in January and fortunately allows people who are applying for PR to use it- I'll be doing so myself. As the processing time is 6-7 weeks I should get this in March whereas my PR would be scheduled for the summer. It only costs around £100 so it's worth it even if I end up with one week between the two and am working.