Comprehensive cover means you are covered for your own car as well as other cars involved should you have an accident.
You will also be covered for any damage to your car such as vandalism, theft of the stereo system, or if you spilled paint over your interior. You will normally also be covered for damage to your windscreen. Most insurers have a deal with a specialist glass firm. Should you need a window replaced, you can normally get it replaced with this company if you pay an excess of normally around £50. Normally a small chip or crack will be repaired for nothing.
Even if an accident is not your fault you will have to pay an excess, this is because you have entered into a legal contract which states that if any claim is made you will pay a set amount of money towards each claim. If the accident was not your fault, you will be able to claim your money back from the person’s insurance company who was at fault.
You should keep in mind that your insurer only covers you for accidental damage to your car and you are not covered for typical mechanical faults or wear on the tires etc.