The Eng Tec scheme is very good and accredited and as the other have said the T&Cs are very good compared to other engineering career options.
Two things to add one make sure that when you apply make sure that you only use "NATS" we were rebraned a few years ago and dropped the national bit and just to state the company will be reducing the number of 24 hour engineering watch staff so if that is what you are after the opportunties will be limited, otherwise its a very intreseting career.