Thanks Sady. Even though it’s only a prediction, 12.6 wouldn’t be too bad. Someone I know who does athletics and is the same age as me ran the 100m in 12.4 with training.
Again, I want to thanks everyone for their advice and suggestions. However, I apologize that they have gone to waste. Even though I love sprinting, when I think about it, I realise that sprinting just isn’t my thing. 
Hopefully, in the future I can change my mind.