I'm non British and I can understand your frustration. I haven't looked into any details but I'm pretty convinced that KLM/Air France, Lufthansa etc is open for anyone, including British citizen, with the note that you have to speak their native language to pass the selection. The same applies to BA but "unfortunately" you happen to speak the "world language number 1". Most non native English speakers has put down a tremendous effort to get the standard up to an acceptable speaking level and you are more than welcome to get the German, French, Spanish etc up to an acceptable standard. I don't think Lufthansa would turn you down if you passed their DLR test and spoke fluent German.
Good luck!
