Hi Les,
I'm a Tube Train Driver, Its a good job, good pay, good conditions, but the only way now-a-days to get a job on the Underground, is by going through TFL, they are not taking on direct recruit drivers at the moment, the last time, they kept going through red signals, and generally not understanding the job, you'd be surprised at how much, and what you have to learn.
Having said that, they do, every so often, re-attempt with direct recruit drivers, so good luck.
ps,
If you want to know more about the ins and outs, post back, i'd be happy to oblige.