81% average last July and that was only their second month of operation. I'd expect that to be higher this year accounting for some modest growth, but thanks to the CAA's continued incompetence in publishing the route stats we won't know anytime soon...
It's reasonable to say that certain flights on certain peak days will be full at this time of year.
I have yet to hear anything concrete on why the A346 was sent. It may be the A332 was overbooked, the seat map on EDI-AUH was showing surprisingly few empty seats on the A346 given it was a short notice switch from A332 (not an exact science I know but gives an idea).
On the other hand it may be that they are suffering some sort of A332 availability issue just now, which would seem strange given the number they have in their fleet, but there was also an A333 substitute a couple of weeks ago so it hasn't been a one off.