Well, if you go on the Emirates homepage, an African girl is smiling at you in Emirates uniform... (All the models are Emirates cabin crew.) Emirates does hire boys and girls from all over the world.
Welcome to Emirates Group Careers Centre - Work for Emirates
However, there are thousands applicants for each AD in the African countries, so it's quite difficult to get an invite!!! It's also difficult to be chosen as there are hundreds of applicants at the assessment days. It's harder for boys as 75% of the crew must be female, so they obviously hire less boys than girls.
You said you work for a British airline but I don't know where you are based. If you have a chance to go for an assessment day in the UK, I would rather try that if I were you.