Clearly you would need to retake a CBT and be limited to 125cc forever more if you didn't take your bike test. Plus you would have to pay for a new CBT every 2 years.
When you get disqualified from driving and are ordered to take a test to get your licence back then that's exactly what it is. You are no longer a qualified driver. Post your ban you are a learner driver like a 16 year old is.