To be fair, technical skills training in the UK is currently mostly delivered through apprenticeships. The model is 80% "on the job", 20% "off the job" training. So, in theory at least, they should deliver the kind of experience and informal mentorship you're talking about, alongside classroom based training (which is supposed to cover fundamentals, theory, etc.).
In practice, how well this works depends on how effectively employer and training provider coordinate, and how committed the employer is to delivering on the mentorship part.
In practice, how well this works depends on how effectively employer and training provider coordinate, and how committed the employer is to delivering on the mentorship part.