This is why for night flights, I avoid sitting close to the galleys - I have had this issues not only on BA (and even in First), but also on TK, Air France, KLM, and even a few times on SQ, CX and JL. I can understand the need to still continue service or keep one self busy/entertain during down time. However, I do not understand why they can't remember that there are pax trying to sleep, therefore, they could keep it to a minimal or speak softer and be more careful with the cutleries/plates/cups and doors.
I believe the best in all my experience where I've never had any disturbance at all was with LH and LX in F - especially with the thick cabin curtain separating the galley to the cabin.

Cheers!