Thanks for your replies. Indeed we would have needed to pay for the bulkhead seats. However, as no one had paid the extra on our flight to Tokyo and myself and my wife weren't seated together we were able to request seats (51 D/E) which were reserved for us straight away and able to move after take-off! Fantastic service from the predominantly Japanese crew onboard.
Upon leaving after the earthquake we were just happy to have a seat onboard and somehow that puts everything into perspective!