Plkease excuse me I'm going to offend some people here. I did C&G/NVQ2, 2 years 1 day a week.
I'd read the book the weekend before the course started, so learned nothing knoledge-wise about pipe plumbing (ie a bit about lead) from the course itself. I learned plenty by asking questions about other stuff, from the lecturers who were ex plumbers. The course material is trivially basic. It is intended for school drop-outs so it isn't surprising I suppose.
2 parts of the corse are "number power" and "word power". Can you add up/use a calculator, and can you understand basic English?
Possibly the most useful part for you will be the chance to use loads of pipe to practise bending. But you could spend £20 on 30m and get much the same benefit, if there was someone handy to help if you had q's about that.
So without the "craft" aspects , of lead, and bending of copper, I believe its all tooo simple stuff. Practise is all very well, but you get v little of that from the course itself. If you're doing it while getting experience working for someone, that's the useful bit - the course doesn't help. It enforces a structure but includes too much you may not want to know about so will waste time on (Lead/roofing, lead for drainage).
One exception - I learned a fair bit about about H&S regs& law - though a lot of that would be covered by common sense.
NVQ2 is neither a necessary nor sufficient qualification to be a plumber.
NVQ3, goes off onto more commercial scale stuff - more interesting but not much relevance to domestic. And you still have to do some lead bashing!
None of the above tells you what bits to buy to fit a bathroom - a
Wickes leaflet would be better. Then a load of manufacturers' leaflets to see what you can theoretically get, and a visit to an actual plumbers merchant to see what you can actually get.
Then you fit the bits together and it works as long as you remember rule number 1. - Sh*t goes downhill, except when it's coming in your direction.