Just another thought here. I know the question was about pay at BA but have you considered other airlines? It is highly unlikely you would get a job with BA straight off. Airlines like the holiday companies (Air 2000, Monarch, Britannia etc.), the low cost carriers and people like BMI start their FOs on around £38k+ On top of that you get your allowances, share options, and lots of other benefits. Also, time to command is alot shorter than at BA with most of these airlines, and you would then see your salary increase by a large amount. There is no bidlines at these companies and so everyone does their fair share and being junior doesn't mean you'll get all the crap flying.
Just a thought.