People will always need plumbers so yours is a good choice, but you'd be wise to think flexibly about work. For example, house building has slowed down these last 5 yrs, but heritage and regeneration work is fairly buoyant and office and commercial buildings are still being refurbished.
Of course the domestic repair market is always there so think about setting up on your own if you're interested in fixing leaks and replacing taps in homes, but be sure you incorporate a bit of marketing and business developement in your training. Research the commercial and regeneration market to find out who the subbies are in your area and check the local recruitment agencies to see what's being advertised. Good luck and more ppower to your elbow (joint)!