Hi there, I think the best thing to do is make a note of all of the train stations within an hour of where you live. Then Google search "train operating companies that serve" + the station names individually. Once you have that list of companies, search their names plus "vacancies".
Just be aware that recruitment may be on hold until later in the year, and that there is a lot of competition for trainee train driver roles. Having said that, do your research, work on your CV, keep applying and as long as you have a good work history, are in decent health and haven't any addictions to drugs or alcohol you have as good a chance as anyone out there.
All the best!