Thanks a lot for taking the time to answer this question Edgardo.
Looking at your modified worksheet however, I see that after the call to Library:-SortProducts, which results in Eq. 8, the products are not in fact written in the "correct" order. For example look at the 2nd and 4th terms in the second-last line. We still have terms like:
Dagger(a) a Dagger(a)
which clearly are not in normal order. There are other terms containing operators b which are also not in normal order (look at line 2 of Eq. 8).
The same follows after the simplification in Eq. 10 (see lines 4 or 5).
So my question still holds in a sense, if I'm just missing something, or at this stage it's not possible to write this expression in the normal order automatically (i.e using SortProducts or equivalent)?
... and thanks for all your work on the physics package!