A MOT test is an annual test of vehicle safety, roadworthiness aspects and exhaust emissions required in the United Kingdom for most vehicles over three years old. It is required by law if the vehicle is going to be used on public roads. Once a vehicle is over three years old a new MOT test will need to be carried out every 12 months.
If you take your car to a main dealership or a garage which is part of a chain then you will likely receive reminders to tell you when your MOT is next due. If you use a small independent garage this may not always happen. The DVLA do not send out MOT reminders so it is your responsibility to check that the MOT is still in date. The easiest way to do this os online through the Government website. It is free to do and the only information you need is the registration number of the vehicle.
Driving your car without an MOT will not only invalidate your insurance in most cases but can also land you with points on your license and possibly removal of the vehicle. You will then have a certain amount of time to go and collect the car from the impound. There will be a charge for this which can sometimes go up into the hundreds.