Natural sciences is a broad course which encompasses all the sciences and you specialise in later years. The likelihood of being unemployable after doing natural sciences is very low. Career paths include science (obviously), management, finance, law (with a conversion course) and all sorts of stuff like that. Engineering is the same. Just because you're doing engineering, doesn't mean you'll become an engineer, it opens doors for all manner of careers, provided you do well enough in your degree.
As for what's most enjoyable, with natural sciences it's nice to be given the flexibility to choose later on when you have an idea of what sciences are like past A level. Things change a lot and people's opinions of where they want to go change.