Yes, that's correct. Having passed your ATPL(H) exams using the interim procedure they will remain valid for the issue of an ATPL(A) or CPL(A) for 36 months from the date of your last pass. It is treated as a new round of exams, you get six new sittings and four attempts at each new paper.
If you are wealthy or lucky enough to get an IR(H) in the 36 month period the issue of an IR extends the validity indefinitely.