The only way to get into dispatch in BA is through the ranks. Most of the dispatchers i've spoken to started as customer services agents, then on to reservations, possibly senior customer services agents, followed by some back office work (what we call Close-outs), and finally on to dispatch. Mind you, this is over an average of 5-8 years - with the exception of a few dispatchers who already held active CAA dispatchers' licences - good luck.