OML
I've had varying advice on this issue, ranging from 'forget it' to 'go for it'.
There are many commercial airline pilots with OMLs, but almost all of these will have got the OML after starting work.
With regards to CTC et al, you have to ask them. The law is unclear here, you can't discriminate against someone because of their age, so why is it OK to stipulate an OML with no restrictions when the CAA/EASA have given someone a Class 1, albeit with restrictions. An OML covers a vast range of conditions.
Also, I know of someone with an OML about to start their FI course at a big FTO in southern England with a view to instructing at CPL level.
So lots of hope, but as ever in aviation, there will be some hurdles to jump.