Civil Engineering will always be more stable but Mechanical Engineering can offer a lot more in terms of job oppurtunities.
Do NOT study mediocre a level subjects (biology, english, art, history, chemistry etc.)
If you're smart and able to handle the work load, go for:
- Maths
- Further Maths
- Physics
- Engineering or Design (if your college provides it)
If you are studying 4 A-Levels, get ready to say goodbye to your social life. No more going out on a bender on the weekend, no more nandos, just straight revision every day of the week. But it'll all be worth it.
Choosing Maths and Physics will keep your career paths very open. You could go into Finance, Engineering, Astronomy, Statistics, System development, Game development, Software development, Piloting etc.
Stay away from biology and chemistry, do not fall in to that trap. The boring options will reward you the most.