Sounds like a flat battery. Did you leave any electrics on overnight ?
I think it would be best to try to start the car with jump leads and take the car once started for a run of 10 to 15 miles then try to restart the car once back at home.
The MOT place may have left a door open of light on for a long time and run the battery low.
If car will not start on return from run then the problem may be faulty battery or drive belt alternator or jammed starter.
maurice
February 2010