WOS,
you really are making this more complicated and expensive than you need to. Find a Microlight school, do the NPPL (M) and get converted onto your machine. If the weather is nice I will come and do it for you, a trip to Scotland would be pleasant!
The ML course is 25hrs, if you are capable and a quick learner you will go through in close to those hours. The cost in a ML as opposed to a SSEA is significantly cheaper.
There are plenty of places in the sunshine who would get you through in a 2 week holiday and the whole lot including the holiday would be cheaper than going through the SSEA then convert to ML route.
The cost of paying for an Instructor to convert to being an ML Instructor would cost more than doing the lot in the sunshine.