There has never been a worse time to be a plumber.
Working class jobs without a degree will get you minimum wage. Government have turned a blind eye to the plumbing industry, because colleges are making £millions and creating growth, jobs and 'mythical' futures for people [the working class have not caught on to this wheeze yet].
Tutors, career guidance and course vendors will say that there is a demand, or a skill shortage - they are not telling lies - but, there is always a skill shortage, because the government say "skills = growth". Hence, we can never have enough growth, so we can never have enough skills. So there we have the meaning of the skills shortage, and it does not mean there is a demand for work, it just creates statistics for economic theories like 'human capital' - see the Wolf Review 2011 for more on this. Wolf pointed out that there is already an oversupply of labour with intermediate qualifications NVQ3/4 in the UK.
There are other ways the media use 'skill shortages' such as reporting that youngsters cannot come into the trade anymore, because of the dearth of qualified workers looking for jobs, and willing to work for near minimum wage. Thus, the headlines of 'young people not entering trade' because of lack of opportunity - next headline - not enough young people coming into plumbing!
If you are going to pay to learn something, then get a degree. Although you have to pay back the loan, a degree has a 'lifetime currency' so it will always help on your cv to get jobs anywhere in the world. Note: vocational quals have dubious currency - you will have to re-sit every 5 years and qualifications up to NVQ level 2 have no economic value at all (Wolf Review 2011). Contact the workers education association for help with getting onto a degree pathway.
If you get an 'employed' apprenticeship with an employer, it is different, and your vocational qualifications suddenly become valuable at level 3 and above. Without the apprenticeship, you are getting something that will not be recognised as a qualification [technical certificates done in 12 weeks, a year, or two years are not identified as having any value, according to employers].
During my 30 year career as a plumber, my qualifications have meant nothing. They do not get me more work, nor do the inform the customer that I am capable, or offer a better service than the other guy, who did six weeks. Hence, no point in getting a qual that people just don't give a damn about.
Finally, imagine being a job you love and doing the job to the best of your ability - you use the best materials, and work to high standards. Then imagine competing against and being undercut by a continual supply of cheap labour from europe, or from operatives from six week training courses who want to work for free. Do you want to get to the top of your game, for this to happen? In addition, if there are no barriers to entry, e.g. no experience needed, then anyone, at anytime can set up in business and make things difficult for your business.
Consider my advice and go for the degree at all costs, and avoid anything with 'vocational' in it.
