Admit to freezing episodes to the DVLA and see what they say. Freezing comes on suddenly and could do so when you are driving and unable to pull in somewhere; dual carriageway, motorway, heavy city trafffic.
You summed it up concisely... the unpredictability of the condition, and,the implications of wearing off periods. Think what may happen if you haven't disclosed the full facts to the DVLA, your freezing episodes, and you have the misfortune to be involved in accident, which may not be your fault, but they look more closely at you and the incident and your Parkinson's is discovered. Maybe that accident caused a fatality. You would have to live with that for the rest of your life. Well, that's up to you but from what you have described of your condition, think seriously before getting behind the wheel again.
As Island Mike said, if you fill in the DVLA form and do not admit to freezing episodes I think you may be on very dicey ground and possible prosecution for not declaring the fact, as may your neurologist as they also have to fill in a form declaring your fitness to drive.
I think that you are being at the least reckless, and, at the worst, irresponsible, and also setting back the cause of those with Parkinson's who are responsilble and honest in their dealings with the DVLA, and other organisations in their actions, but when they find out about those that choose not to disclose their true situation, and tar all with the same brush of hiding material facts, everyone suffers the same fate.
I liken this to PIP claims that are exaggerated and submitted far too early to be accepted, thereby jeopardising the chances of those that really qualify.