What class will you be flying?

ABZ - LHR - xxx - PER on BA for the first two legs (but has to connect in Asia, think SIN or HKG) and then another OW carrier for the third leg would give you the 2x 32kg bags.

ABZ - LHR - xxx - PER on QF would give you a weight allowance of 45kg.

ABZ - LHR - DOH - PER on QR would give you a weight allowance of 45kg.

ABZ - LHR - HKG - PER with LHR - HKG being on CX would give you a bag allowance of 2x 23kg bags.