To be honest if the truth is known i think many plumbers frown upon these coarses because middle aged men with a drive to succeed are retraining and entering there trade, i appreciate that there will be some muppets slip through the net, but why would i put myself through this and not want to make a go of it? It shouldn't be so cut and dry when it comes to employment no one will have a chance.
When it comes to employment, the difference between someone who has done a course (fastrack or spun out over however many years) and someone who has followed a recognised apprenticeship route is experience. This experience is passed on by other tradesmen over a period of years.
Giving people chances costs money and customers. No employer in any line of work will normally take on someone who cannot do the job they are employed to do and loose customers by sending incompetent people to do it. Remember most plumbers will be working on their own most of the time with no one there to help when things go wrong so you are expected to know how to deal with any situation you will find.
Only an exceptional few, no matter how much drive or commitment most may have, could do this and take up an employed position where you would be expected to be sent to and deal with any aspect of the trade. Classroom scenarios and even worse computer based ones, are nothing like real life.
There are proper employed adult trainees within the industry, employed in a similar way to apprentices (albeit on a higher pay rate) gaining on the job experience over 2-3 years. Unfortunately there are few being taken on as the work load at the moment does not require it.
The experience gained from the so called placements offered by training centres is limited and tailored to get you past the bare minimum requirements. The theory side of things is the easy bit and can be learned by anyone with a half a brain. Actually knowing how to do the job or having the practical skills to do so is not something taught in a classroom. Having done an apprenticeship shows your perspective employer you have been done the industry recognised route of qualification and training and have gained experience in doing so.
By all means retrain and do this but do not expect to be able to be employable for a long time after it unless you fall into the exceptional category in both skills and luck.
You will probably have to go self employed and do your real learning at your own and your customers expense.