You're wrong about having 2 years to start training at a unit. I wish that was the case!!
You have 9 months to start a unit UTP from the date of finishing a student rating course, If you dont mange this then a APC is required (a minimum of 3 days btw). The student licence is valid for 2 years but you can apply to the caa for an extension on this if youve done APC's etc.