jam123
Firstly this would be better suited in the Wannabes forum, which is where the Mods will surely move it to. That is also the forum where you can find the answers to your questions by reading the threads there. An "am I too old" thread is running there right now.
Briefly to answer your questions.
1 you are not too old but it won't be easy
2 your GCSE results are unlikely to be of much interest to the airlines.