I know jusy how you feell!
I have also been on CPAP for just a couple of months. I informed the DVLA via their online form . I may have been a bit hasty, as I was not
excessively sleepy during the day - just fatigued, and I've since read that you should wait for your Doctor to either inform DVLA or tell you that you need to do so.... (Its apparently excess sleepiness they are worrid about, and the chance of falling asleep at the wheel)
I got a letter from DVLA stating they would need to contact my Doctor (at Papworth Royal Hospital) to confirm that my OSA was under control - and have heard nothing since. I have not been called back to the hospital for a review, so it looks like they leave it up to the patient. If you have problems give them a call - but if not - good luck to you, you are on your own!
My feeling is that what you need do is use OSCAR and keep a full record showing that your AHI remains below 5 and that you are using the CPAP every night. If you have that, I really can't see how they could take your licence away, as you can document your condition, proving compliance with the therapy - I would challenge any doctor to look at your stats and say otherwise.
I know it is a worry. I'm retired, but even so, losing my license would be a real disaster! So, be pro-active is my advice and build up your own evidence. I also believe it is quite unusual for anyone to actually have their licence taken away. If it did happen, I guess they would be doing you a favour, as you would definitely NOT be safe on the road...
At the end of the day it is our own personal responsibility to be sure we are fit to drive - no matter what a doctor or other professional might say- would you drive if you were ill or had a drink or two? BTW Have you ever done any advanced driver training? IAM or Rospa (Roadar)?
If not, think of doingso, as it costs very little, is fun and rewarding to do - and makes your case even stronger when you are able to say you've under taken training and found proficient in Advanced Driving, after a test given by a Police Class One licence holder and serving Traffic Officer! How many people can say that! (You may well get a discount on your insurance too!)
Cheers!