If I was 19 I'd be getting a trade like a plumber or a bricky! But if you want a job on the railways, theres other roles such as gateline staff or platform staff that would give you experience. Take a bit of time to look at other topics on the forum and what other jobs people have been applying for to give you more of an idea. I worked in a kitchen before the railways, think that helped me getting on the trains, alot of similarities, safety, following procedures and so on.
My training took round a bit a year, was round about 5 months in the classroom, then 7 months learning routes and driving trains with a mentor driver. The railway companies pay for all the training, and in fact you get paid whilst your training so not a bad thing.
I don't work away from home, all my shifts start and finish at my home depot. Just some weeks I start work mid afternoon, and finish at midnight. So by the time I get home my partner is in bed, then by the time I've woken up shes already gone out to work, then when shes got home I've gone to work.
In general, the railways are a very good job to get on, but its hard to get into.