Advice on the demands of the Trade

I just passed my entrance exam for the recruitment that I am in. I am super excited and looking forward for the chance to interview. I have an issue I have been planning on a mission trip with my church for about 3 months my interview falls the 3rd day I would be out of the country. I am aware of how big an honor and opportunity it is to even be considered for the apprenticeship program. I get that the money is great. My major question is the expectation that you do not have a life outside of the trade or is this something that changes after you make it out of the application process? I am not afraid of the work I know it will be difficult in ways I probably do not understand yet. Just wondering if the you are a number not person something that eases with time or if that demands of the trade will always come first regardless of how much planning and communication happen? Brings to mind the concept of having golden handcuffs on or that you can make great money but never the time to spend it or enjoy it. Hope my questions made sense looking forward to getting outside perspectives.