If you are HBO there should be no problem, so long as your incoming BA to TXL is not late.

LHR flights invariably use A5 and AB AUH flights invariably use A1.

Your passport control on arrival will be at A5, this is the way TXL is laid out.

And the distance from A5 to A1 is about 150m where you will have renewed passport and security at that gate.

So no problem. If you are on time you can even go to the lounge (other side of A up the stairs).