Hi I have job pending medical but on holiday 3rd week of training do u think that matters
Yes, it does matter. If you cannot complete the whole course in one go, tell them before it starts. Every TOC I have applied with provided a opportunity to declare any commitments - why didn't you tell them when you had the interview or accepted the job?
Probably for fear of the employer looking negatively at it which I think is understandable.
In any case, if they haven't specifically asked the question or stated when the training starts then I certainly wouldn't volunteer the information.
How about letting someone else who isn't going to mess the company around have the job? I have no doubt the TOC would have asked for details of any outstanding commitments - given that railway jobs tend to be oversubscribed, they can and will find someone who is honest and committed to the job - unless perhaps the holiday is being taken for bereavement/compassionate reasons.
I was never asked (either on application or interview) if I had any holiday booked. As I said, if they don't ask I don't tell and its hardly messing the company around.
Its a bit different if they do ask and you say you haven't any commitments when you actually do.