this depends on whether you apply for a general engineering degree (i think the only respectable one out there is from Cambridge) or you chose a specific type of degree to begin in the 1st year.
Cambridge you try everything for 2 years, and specialise in the last two.
most other places, you will be doing what you wanna do most for 4 years (or 3 if you're a slacker doing a BEng)
Engineers can work pretty much anywhere depending upon the type of engineering they go into.
My dad's an electrical engineer, and he can work in a factory (he has a desk in the corner to design stuff) or he can go up to a recording studio if someone wants him to come out and fix something (because he specialises in recording equipment).
Civil engineers are usually based at a desk, but often they are required to go out and visit construction sites where their work is taking place.
and, a domestic engineer stays at home, occasionally doing the shopping, picking up the kids... ahem.