Rated People is not a construction company itself but more like an agency that puts the right traders in touch with the right customers.
It can be really hard to get that initial foot in the door when trying to get into the plumbing industry.
I would recommend that you contact all of your local traders and offer to help as a labour/plumbers mate even if it's for free, that experience invaluable, it may even lead to a proper apprenticeship.
you really need to show that you are outgoing, dependable, have good initiative and a can-do attitude. (tea making skill essential)
Put a good CV and covering together and drop them off in person at all your local mechanical engineering companies, you could even put some flyers together and hand them out at your local plumber's merchants. get talking to them and show your face even help them load up the vans.
you don't know who you will meet, might even be an MD picking up some bits for a job.
Just do it.. go for it...
I wish you the best of luck