BA aircraft all have universal mains sockets that accept US/Japan, UK/Singapore/etc, EU, and so on.

If you have trouble getting a laptop to work, then try plugging in the power supply to the aircraft before connecting it to the laptop, or disconnecting/reconnecting from the laptop after connecting to the aircraft, etc. The start-up current spike for some power supplies when connected to the laptop can make the aircraft turn off the socket, while powering the power supply up before connecting the laptop load works better.