Rumor, just rumor!!!
The military wobbleheads are in the same quandry as yourself, with the issue of an ATPL (H) against helo hours but carrying forward no dispensation against and ATPL(A).
The CAA has mumbled something about 'up and coming' ATPL(H) to ATPL(A) bridging exams which I am led to believe will consist of the Perf exams and the fixed wing P of F.
Talk to the CAA about it because the more pressure we can bring to bear against them the quicker we get the results.
An ATPL is an ATPL regardless of how the machine flys!!!