If you are caught without insurance you will get fined and will have penalty points put on your licence.  According to BBC's Newsbeat, more than 400 cars are being seized by police each day because their drivers aren't insured.

There are three different kinds of motor insurance which offer different levels of cover:
Third Party Insurance
This only pays for damage caused to other people or their property.  This is the minimum level of insurance cover required by law.

Third Party Fire & Theft
This gives you further protection by covering you against theft or fire damage to your own vehicle.

Fully Comprehensive Insurance
This is usually the most expensive, but covers the cost of accident repair damage to your own vehicle as well as compensating others for injuries or damage in the accident.