I mostly agree with the above, when you get the V5C and registration number the car will have an official date of first registration. This will normally be around the date of your IVA pass, and I believe the first MOT is then due three years after that. However, you should not use the car on the road without insurance. Anyone that needs to take a car for an MOT must have it insured, third party insurance allows you to drive TO a station for a definite timed appointment by the most direct route. My car is on SORN at the moment. It must be insured to take it for an MOT before I can tax it again.