Are you sure that CX still offers F on BNE-HKG? I tried to buy an F ticket for this route and it wasn't available (maybe only some days of the week? It is one of those weird routes that sometimes is nonstop and sometimes one-stop, through another city in Australia). I think CX has F only to SYD and MEL (definitely not on all flights to Australia).
Otherwise your routing looks fine. LHR-HEL-LHR is a nice trip and you do have one more stopover allowed in Europe (as well as 2 flight segments).