"I am 99.9% sure that it states 'all turns within the ATZ are to be made in the circuit direction'."
At an airfield with ATC, I join and turn in whatever way the ATC tell me to. Often both right hand and left hand are in use, with downwind and base joins, and jets etc straight in on the ILS.
I too am very dubious about overhead joins at uncontrolled airfields. Mixing of high wing and low wing in the descent, with the possibility of some being non-radio, appears the most dangerous possible way of joining. I prefer the US way, but do overhead joins here as required.