There is no such thing as a 'Group A aeroplane' anymore, nor has there been for many years - except in the mind of a few PFA fossils.......
For NPPL, it's a 'Simple Single Engined Aeroplane' (i.e. < 2tonne MTOW, 4 seats max)
For JAR-FCL, it's a 'Single Engine Piston' class of aeroplane.
Enjoy flex-wing microlighting - and the rest of your flying! Once the next ANO amendment has been incorporated, you'll find keeping both your NPPL ratings much, much simpler than it is currently!