If you really want to do the jobs and if you are good enough to get through the selection procedure, there's no reason why you shouldn't succeed and the very best of luck to you.
With regard to the salary, there' no doubt that it's a lot less than it used to be but bear in mind that your potential employer is going to spend many £1000s on your training, (in real terms around £40 to 50K), in any other industry you'd get a lot less as "an apprentice", many of us got our licences by paying for our own courses or taking up offers from Serco et al, and living on no wage.
Never assume you deserve the top rate from day one, you won't get it anyway.
It really depends on how seriously you take the profession, you have to be on top of the situation all of the time and be able to make right call every time, during and after your training.
It's not a career you can take lightly, you can either do the job or you can't, if you are determined, you'll get through, if it's just another whim, forget it.
That's the reallity of the job, good luck anyway.