My experience is in large heavy machines, operating / driving them, lifting ops. But all that experience is probably worth next to nothing as I haven't got any tickets or any qualifications on paper. I am willing to pay for all the courses I need to do. Or am i barking up the wrong tree???
Quite the opposite I would say.
That sounds like excellent "safety critical" experience very relevant to the railway. Certainly if you were applying for a safety critical role such as driver it would be looked at very favourably.
Southeastern have been recruiting recently. Faversham and Gillingham would be your local depots. Worth keeping an eye on their website.
This website is an excellent forum for advice/discussion and is a goldmine of information about the different jobs available on the railway, what they pay etc.
Good luck with it!
EDIT TO ADD: no need to pay for any training courses, certainly for operational roles. The key thing is to get accepted onto a training scheme and the training is provided and paid for. In the case of driver training, it can take a year to eighteen months to complete while being paid a salary of £25kish so that's something to consider if you're taking a pay cut, which if you've been working in the oil industry I expect you will be!