Sole ownership simplifies life, but realistically, you're still a long way from any school and your aircraft is not ideally suited to long surface trips.
I think you might well be still better off doing most, if not all, of your course elsewhere, then coming back and either completing with an "imported" instructor, or converting once you have your licence.
Another, and possibly more practical option, is to see if an (the?) instructor at Highland Flying School at Stornoway could become microlight rated (presumably at your expense sadly), then teach you on the Challenger?
G