There is a similar post that was written back in Sept 2018 by someone with lots of good info (link below)
For what's it's worth I couldn't get a medical for over 2 yrs due to Heart problems. And although I evetually got an unrestricted class 1, it wasn't an easy road on deciding whether to carry on.
As I understand it (I'm happy to be corrected) an OML on a medical simply restricts the individual from single pilot commercial operations, and from flying with another pilot who also has an OML. I know a few people who have them, I wouldn't worry. The CAA would not issue the Class 1 if he isn't fit to fly.
Issued my Initial Class 1 Medical with an OML restriction. Best course to take?