I doubt whether the OP will be able to acquire 100 hours PIC before he finishes his University study in three years time.
But even with 100+ hours you've got to do three written exams (not just one as you suggested), plus the RT practical and the PPL skills test:
- Air Law (LASORS C1.3)
- Human Performance & Limitations (LASORS C1.3)
- Communications (LASORS B1.4)
So I still maintain that going from an FAA PPL to a JAA PPL is hardly what I would call a straight swap.