While studying at St Andrews I have been employed as a tutorial assistant for the following undergraduate modules:
There is much extra help available on the material in modules MT1001 and MT1002 at http://www.mathcentre.ac.uk/, including notes, exercises and even video tutorials for your iPod. The benefit of actually seeing someone doing mathematics should not be under-estimated.
If you need convincing of the interest in studying mathematics then you need to visit the fantastic Plus magazine. They also have a good selection of interviews about careers that use maths.
Finally you can find a very useful list of (free) online textbooks in many areas of Mathematics here.