Paul,
Given your plans you do need to think about how many of your training hours can eventually be credited towards the JAR PPL.
It is easy to add the SSEA (aka SEP, aka Group A, aka light aircraft!) rating to a microlight NPPL without too many extra hours, but when you want to upgrade from that to the JAR PPL you'll still need at least 45 hours total flight time of which at least 35 must be on SEP aircraft. That has to include at least 20 hours with a
JAR qualified instructor and 10 hours solo. You do however get the concession that you can claim 10% of your 3-axis microlight time, up to a maximum of 10 hours, towards the JAR licence. See Section C of
LASORS for the details of all this.
You will also need to do all the JAR exams on top of all the microlight ones you'll already have done.
What all this means is that somewhere along the line you're going to have to find a JAR instructor at an approved flying school (a 'registered facility' in CAA terms) and pay for at least 35 hours in a light aircraft no matter how much microlight instruction you've already paid for.
Given the path that you have mapped out for yourself, it might be better to start on the JAR path in the first place.