Hello
I have a c230 coupe and had a leak externally on the head gasket which was small at first but did not get it fixed in time and it started leaking oil and coolant.
The check engine light only recently came on and still functions unnoticeably different with no smoke issues.
Now my question is, if I pay to get the gasket fixed will the engine operate at a decently function able level or is it too major of a issue?
I was quoted by various places between 1500 - 2500. Also worth noting was at the last oil change they mentioned a rear transmission leak.
I appreciate your help as I am in a bind and need a working automobile daily.
Thank you

It's really your choice. Fix it now before it get's even worse or let it go until the engine gives up. It's not going to get better.

So even if I get it fixed the damage is done and the motor is going to die?

Not necessarily. Before replacing the head gasket your technician will check for cracks and plane distortion. Provided the head is not warped (which it quite likely could be - not necessarily an expensive fix) it will be a gasket replacement and everything should be normal. It all depends on what caused the original leak. Get it checked before causing more damage which will obviously cause the repair to be more expensive.