I had the same problem with a wrist injury which put me out for a long while. If you're unfit for over the old 20 days, you'll have to ring up the medical dep. at Gatwick. They will temporarily suspend your medical until you get signed fit again by your local AME, after you have recovered. He will then inform the CAA that all is well, and you'll be back in business!
Far be it for me to suggest some slight rule bending, but 6 weeks sounds like a long time for a wrist to heal (done it several times myself!!), and you could save yourself a lot of effort if you kept quiet. However, if it will be 6 weeks, you should probably let them know.
Hope that is of some help!
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I'm on my way!