chavienne, after being in the airline industry for many years (and in several different countries) I can tell you that the chance anyone would know that you said 'no' to the tattoo questions would be very small. I doubt ground trainers would have access to your application form or interview notes. I've worked as a ground trainer and never had access to this type of information.
You will soon find out that in the airline industry the right arm has no idea what the left arm is doing!
As long as it can't be seen when you are in uniform I don't think you will have anything to worry about. Have fun
