If my branch lacks a SWIFT code, can I use the main HBL Pakistan SWIFT code for transfers?

Your branch is not even expected to have a SWIFT Code. Chances are wherever instructions are being asked for SWIFT code, HBL’s SWIFT code for Pakistan should suffice.

However, it is always a good idea to obtain international wire transfer instructions for your account from HBL, they will provide you with the instruction set in many languages and this ought to contain the SWIFT code.