Well, firstly don't bank on feeling the urge to get a PPL(A) once you have more money, you'll be amazed how much fun flexwings are.
I learned on "conventional" aeroplanes and did a flexwing conversion some years later, this took me about a dozen hours. Irritatingly most people going the other way seem to find it much easier.
Flying flexwings will, cheaply, teach airmanship, weather, RT (if you use a radio), navigation, airfield procedures, and a whole stack of "I learned about flying from that" stuff. It's also damned good fun.
In doing your JAR group A license, what you'll need to learn is:-
- How to handle the different aeroplane.
- An obsession with runway performance planning
- Some different air law
- More complex (but not necessarily better) navigation methods.
- How to fly more procedurally.
None of this is incompatible with what you'll have done in the flexwing, in fact pretty much all of it is complementary. Then, so long as you stay reasonably current on both, you'll be pretty safe on both - just don't fly ONLY ONE for too long without a bit of time with an instructor when you go back to the other.
G