My son had a similar letter but for "marijuana use" .
What he had to do was call the DMP and explain the letter. The DMP said he could refer him to a psychiatrist or he could find a psychiatrist himself and call the DMP's office with the name, address and phone number and he would arrange the referral and make the appointment. You have to see a private one (No NHS) and the report, once completed, is sent to you for approval before being sent onto the DMP. Once the DMP receives it they send it to the Medical Division for the Chief Medical Officer to look at and make a decision on.
In my sons case he found a psychiatrist and the DMP made the referral. It cost £300 including the report for a 1 hour appointment. As you have to go to a private psychiatrist you should get an appointment within a week or so.
We had the psychiatrist rewrite the report because it was so inaccurate (and contravened the privacy laws) - the first one actually said "has mental issues" - when he called their office the secretary apologised and said it was a typ0 - it should have read "NO mental issues!" As you can imagine, I was very angry about that as it could have meant him being refused.
Once the report gets sent to the Medical Division it will take between 4-10 weeks for it to be assessed. (I wrote e-mails every week asking for updates - my son's was reviewed after 9 weeks) and once a decision is made it is passed onto the Immigration Case Processing Officer to continue with the application.
You can plan on this delaying things by between 2-4 months, depending on when you are able to get the appointment and the speed of the report being done. In our case it delayed things by almost 6 months, but that was exceptional.
Once the report has been submitted there should be no reason that you can't return to Canada to wait out the results. As a spouse, you are medical exempt but what they are trying to ascertain is if you are a danger to public health or public safety (the only things you can be refused on medically). I wouldn't think you have a problem with either of those, it's really a formality.
Get in touch with your DMP as soon as possible!
this is only my opinion.... CIC are a law unto themselves!
